MECHANICS  DEPT. 


THE  ELEMENTS 


OF 


REFRIGERATION 


WORKS  OF 
PROFESSOR  A.  M.  GREENE,  JR. 

PUBLISHED   BY 

JOHN  WILEY  &  SONS,  Inc. 


Elements  of  Heating  and  Ventilation. 

A  Text-book  for  Technical  Students  and  a  Refer- 
ence Book  for  Engineers,  vi  +  324  pages,  6  by  9, 
223  figures.  Cloth,  $3.50  net. 

Pumping  Machinery. 

A  Treatise  on  the  History,  Design,  Construction, 
and  Operation  of  Various  Forms  of  Pumps.  Second 
Edition,  viii  +  703  pages,  6  by  9,  504  figures. 
Cloth,  $4.50  net. 

The  Elements  of  Refrigeration. 

A  Text-book  for  Students,  Engineers  and  Ware- 
housemen, vi  +  472  pages.  6  by  9.  192  figures. 
Cloth,  $4. 50  net. 

BY  SPANGLER,  GREENE,  AND  MARSHALL: 
Elements  of  Steam  Engineering. 

By  the  late  H.  W.  Spangler,  A.  M.  Greene,  and 
S.  M.  Marshall,  B.  S.  in  E.  1&  Third  Edition, 
Revised.  v  +  296  pages,  6  by^Bk  284  figures. 
Cloth,  $3.00  net. 


THE  ELEMENTS 

OF 

REFRIGERATION 

A  Text   Book   for   Students, 
Engineers  and  Warehousemen 


BY 


ARTHUR   M.  GREENE,  JR. 
ii 

Professor  of  Mechanical  Engineering  and  Dean  of  the  School  of  Engineering, 
Princeton  University 


FIRST   EDITION 
SECOND   IMPRESSION,   CORRECTED 


NEW  YORK 

JOHN   WILEY  &  SONS,   INC., 

LONDON  :  CHAPMAN  &  HALL,  LIMITED 


. 

Engineering 
Library 


Copyright,  IQTS,  1919 

BY 

ARTHUR  M.  GRLENE,  JR. 


PREG3   OF 
I/2A  BRAUNWORTH    &   CO 

BOOK    MANUFACTURERG 
BROOKLYN,    N.    Y, 


PREFACE 


The  aim  of  the  author  in  preparing  this  book  has  been  to 
bring  together  in  a  logical  order  the  necessary  data  from  which 
to  design,  construct  and  operate  refrigeration  apparatus.  He 
has  endeavored  to  describe  the  apparatus  and  then  to  give 
the  theoretical  discussion  of  the  principles  on  which  the  action 
of  this  apparatus  rests.  A  detailed  description  of  the  applica- 
tions of  refrigerating  machinery  to  cold  storage  and  ice  making 
is  followed  by  that  of  other  applications.  The  author  has 
freely  consulted  the  Transactions  of  the  American  Society  of 
Refrigerating  Engineers  and  the  bound  volumes  of  Ice  and 
Refrigeration,  and  has  gained  much  information  from  these 
two  excellent  publications.  Much  of  the  text  has  been  de- 
veloped in  teaching  this  subject  for  many  years.  Whenever 
the  work  of  others  has  been  used,  credit  has  been  given.  The 
author  is  indebted  to  many  writers  whose  work  he  has  used 
in  the  class  room  and  in  preparation  of  his  lectures,  and  to 
the  manufacturers  of  refrigerating  apparatus  who  have  given 
data  for  the  preparation  of  this  text.  The  aim  has  been  to  make 
the  book  complete  with  the  necessary  engineering  data  for 
problem  work  without  reference  to  other  books. 

The  author  has  added  a  set  of  problems  in  the  last  chapter 
illustrating  most  of  the  computations  which  must  be  made  in 
refrigerating  work.  The  problems  illustrate  the  methods  by 
which  questions  of  the  engineer  may  be  answered. 

The  book  is  intended  for  the  use  of  upper  class  men 
in  technical  schools,  for  engineers  and  those  operating  re- 
frigerating apparatus.  The  work  presupposes  a  knowledge  of 
thermodynamics  and  heat  engineering. 

The  plan  of  the  work  has  been  for  a  continuous  study  of 
the  book  without  any  omission.  The  last  two  chapters  are 


a  r:  3  n  I  " 


iv  PREFACE 

intended  to  give  data  and  methods  for  actual  computations 
and  should  be  used  during  the  course  for  problem  work.  Prob- 
lems based  on  the  text  should  be  given  with  the  study  of  the 
book.  These  problems  should  be  solved  by  use  of  the  slide 
rule. 

The  author  desires  to  thank  his  wife,  Mary  E.  Lewis  Greene, 
for  the  aid  she  has  given  in  the  preparation  of  the  manuscript 
and  in  the  reading  of  proof.  He  desires  to  thank  those  authors, 
publishers  and  manufacturers  who  have  furnished  him  with 
data. 

A.  M.  G.,  Jr. 
SUNNYSLOPE,  TROY,  N.  Y. 
September  i,  1916. 


TABLE  OF   CONTENTS 


CHAPTER  I 

PAGF 

PHYSICAL  PHENOMENA  AND  INTRODUCTION. — Early  methods,  evaporation, 
solution,  latent  heat,  heat  of  fusion,  vaporization  under  reduced  pressure, 
natural  ice,  compression  machines,  air,  volatile  liquid,  general  principles  i 

CHAPTER  II 

METHODS  OF  REFRIGERATION. — Natural  ice,  different  systems  of  cold  storage, 
refrigerator  cars,  air  machines,  open  and  closed  systems,  volatile  liquid 
machines,  refrigerants,  absorption  machine,  vacuum  apparatus,  chemical 
methods 8 

CHAPTER  III 

THERMODYNAMICS  OF  REFRIGERATING  APPARATUS. — Air  machine,  refrigerating 
effect,  cooling,  displacement,  work,  effect  clearance,  effect  friction,  incom- 
plete expansion  and  compression,  moisture,  vapor  machines,  temperature- 
entropy  charts,  Mollier  charts,  dry  and  wet  compression,  absorption 
apparatus,  problem,  multiple  effect 41 

CHAPTER  IV 

TYPES  OF  MACHINES  AND  APPARATUS. — Various  machines,  cylinders,  manip- 
ulating valves,  pistons,  CO2  machines,  SOj  machines,  absorption 
apparatus,  welding,  pipes,  fittings,  condensers,  separators,  receivers, 
coolers,  vacuum  apparatus,  binary  refrigeration,  cooling  towers,  nozzles, 
ponds,  safety  devices 109 

CHAPTER  V 

HEAT  TRANSFER,  INSULATION  AND  AMOUNT  OF  HEAT. — Radiation,  convec- 
tion, conduction,  transmission,  constants,  walls,  partition?,  floors,  pipe 
covering,  doors,  heat  from  machines,  lights,  persons,  cold  storage  data.. .  182 

CHAPTER  VI 

COLD  STORAGE. — Purpose,  laws,  peculiar  features  of  storage  for  different 
articles,  layout  of  warehouse,  construction,  arrangement  of  piping, 


vi  TABLE  OF  CONTENTS 

PAGE 

special  cold  storage,  amount  of  insulation,  indirect  refrigeration,  bunkers, 
fans,  amount  of  refrigeration,  coil  surface,  pipe  sizes,  central  stations, 
automatic  refrigeration,  refrigerator  cars,  precooling 217 

CHAPTER  VII 

ICE  MAKING. — Can  system,  plate  system,  apparatus,  flooded  system,  filters, 
evaporators,  raw  water  system,  freezing  tanks,  expansion  coils,  curve  of 
consumption,  storage 269 

CHAPTER  VIII 

OTHER  APPLICATIONS  OF  REFRIGERATION. — Candy,  breweries,  blast  furnace, 
auditoriums,  rinks,  ice  cream,  shaft  sinking,  drinking  water,  chemical 
works,  dairy,  creamery,  liquid  air 312 

CHAPTER  IX 

COSTS  OF  INSTALLATION  AND  OPERATING  COSTS. — Land,  buildings,  machin- 
ery, supplies,  dimensions  of  apparatus,  power  and  performance  of  plants, 
labor  costs,  load  factors,  operating  costs,  ice  data,  car  data,  ice  cream 
data,  ammonia,  carbon  dioxide,  sulphur  dioxide,  testing  apparatus, 
results  of  tests 343 

CHAPTER  X 

PROBLEMS. — Insulation,  space,  refrigeration  for  rooms,  coil  surface,  pipe 
length,  velocity  of  brine,  bunker  coil,  fan  size,  brine  main  and  pump, 
ammonia  main,  plate  plant,  refrigeration  of  plant,  ice  storage,  cost  of 
pumping,  evaporator,  filter,  compressor,  power,  condenser,^  multiple 
effect,  water  cooling  tower,  blast  furnace  refrigeration,  test  computations.  407 


ELEMENTS  OF  REFRIGERATION 


CHAPTER  I 
PHYSICAL  PHENOMENA  AND  INTRODUCTION 

THE  practice  of  cooling  bodies  below  the  temperature  of 
the  surrounding  atmosphere  has  been  followed  for  ages.  This 
has  been  done  by  the  evaporation  of  a  liquid  as  is  the  practice 
in  Mexico  and  other  warm  climates,  where  the  liquid  to  be 
cooled  is  hung  in  porous  vessels.  The  evaporation  of  the  liquid 
which  percolates  through  to  the  outside  cools  that  remaining 
inside.  In  India,  it  is  stated,  evaporation  from  the  surface 
of  shallow  porous  vessels  even  causes  a  film  of  ice  to  form. 
The  solution  in  water  of  a  salt  like  saltpetre,  or  the  mixture 
of  snow  or  ice  and  saltpetre,  has  been  used  for  centuries  to 
abstract  heat  and  cool  the  liquid  resulting,  or  anything  that 
was  immersed  in  it. 

The  first  method  was  applied  about  one  hundred  and 
fifty  years  ago  in  a  way  differing  from  that  of  the  ancients. 
It  was  then  found  that  evaporation  of  the  liquid  would  occur 
if  the  pressure  were  removed,  particularly  if  the  liquid  were 
ether  or  some  other  highly  volatile  liquid.  This  evaporation 
would  occur  at  such  a  low  temperature  that  ice  would  rapidly 
form  on  the  surface  of  the  vessel  containing  the  boiling  liquid 
if  the  vessel  were  placed  in  water.  It  was  also  found  that 
if  the  vapor  arising  from  the  evaporation  of  the  liquid  were 
compressed  to  a  higher  pressure  than  that  at  which  evapora- 
tion took  place,  it  could  be  condensed  again  by  water  at  ordinary 
temperature,  and  the  process  repeated. 

The  property  of  the  substances  utilized  in  these  illustrations 


2  ELEMENTS  OF  REFRIGERATION 

is  the  property  of  latent  heat.  When  a  body  changes  its  state, 
a  certain  amount  of  energy  must  be  absorbed  by  that  body 
to  bring  about  this  changed  state.  To  change  a  body  from 
a  solid  in  which  the  form  and  volume  are  fixed  and  the  con- 
dition of  the  molecules  is  such  that  their  orbits  are  fixed,  into 
a  liquid  in  which  the  volume  but  not  the  form  is  fixed,  or  the 
molecules  have  orbits  which  have  more  freedom,  requires  the 
addition  of  energy.  The  name  heat  energy,  or  heat,  is  applied 
to  this.  Energy  is  required  to  change  a  body  from  the  liquid 
state  to  the  vapor  state  in  which  the  form  and  volume  are 
not  fixed,  since  the  molecules  have  free  paths.  The  molecules 
are  so  far  apart  that  molecular  attraction  has  been  broken  down. 
The  energy  required  in  the  case  of  the  fusion  of  a  solid  or  the 
evaporation  of  a  liquid  is  used  to  overcome  molecular  energy 
of  attraction,  and  for  that  reason  it  is  potential  in  form 
within  the  body.  It  is  not  used  up  in  increasing  the  kinetic 
energy  of  the  particles  of  the  body,  and  hence  there  is  no  change 
of  temperature  during  these  additions,  and  the  heat  is  called 
latent  heat. 

In  general,  if  heat  be  continuously  added  to  a  solid  while 
the  pressure  remains  constant,  its  temperature  will  rise  until 
the  point  of  melting  or  fusion  is  reached  and  then  the  tem- 
perature will  remain  constant  until  the  solid  is  changed  to  a 
liquid.  The  temperature  of  the  liquid  will  then  continue  to 
rise  with  the  addition  of  heat  until  the  boiling-point  is  reached, 
at  which  point  the  temperature  will  remain  constant  while 
the  heat  is  added,  although  the  liquid  will  be  changing  to  a 
vapor.  The  further  addition  of  heat  will  increase  the  temper- 
ature of  the  vapor. 

The  previous  operations  were  supposed  to  take  place  at 
constant  pressure,  because  to  every  pressure  there  corresponds 
a  temperature  of  fusion  and  a  temperature  of  vaporization. 
These  are  fixed  for  definite  pressures,  and  at  these  pressures 
and  temperatures  the  amount  of  heat  to  fuse  i  Ib.  of  sub- 
stance, the  heat  of  fusion,  and  the  heat  required  to  vaporize 
i  Ib.  of  liquid,  the  heat  of  vaporization,  are  fixed.  Should  the 
pressure  change,  the  temperature  of  these  actions  would'change. 


PHYSICAL  PHENOMENA  AND  INTRODUCTION  3 

In  the  ancient  way  of  producing  cool  liquids,  the  evap- 
oration which  occurred  at  the  outside  of  the  vessel  required 
heat,  and  this  was  largely  supplied  from  the  liquid  within. 
The  liquid  was  cooled  by  the  removal  of  heat.  If  this  removal 
of  heat  cools  the  liquid  to  its  freezing-point  (fusion-point  of 
solid),  any  further  evaporation  of  the  liquid  from  the  surface 
of  the  vessel  would  remove  heat  from  the  liquid  and  cause  some 
of  it  to  solidify,  forming  ice  if  the  liquid  were  water.  In  the 
case  of  salt  being  dissolved,  this  same  kind  of  energy  is  needed. 
In  this  case  it  is  called  the  heat  of  solution.  To  change  the 
condition  of  the  molecules  of  the  salt  so  that  the  molecular 
forces  are  overcome,  energy  is  applied,  and  as  this  energy  comes 
from  the  liquid,  its  temperature  is  lowered. 

In  the  case  of  the  vaporization  of  a  liquid  under  reduced 
pressure,  the  object  of  this  reduction  is  to  permit  the  evap- 
oration at  such  a  low  temperature  that  heat  may  be  removed 
from  surrounding  objects  of  low  temperatures.  Water  boils 
at  212°  F.,  but  if  the  pressure  were  reduced  to  ^V  lb.  the  tem- 
perature of  boiling  would  be  less  than  32°  F.  and  with  the 
evaporation  of  some  liquid,  ice  could  form.  Of  course,  it  must 
be  remembered  that  the  evaporation  of  a  liquid  can  take  place 
only  if  heat  is  added  to  it  at  the  boiling-point.  If  the  liquid 
is  at  the  boiling-point  and  there  is  nothing  from  which  heat 
can  be  abstracted,  nothing  can  happen.  If  it  is  in  contact 
with  substances  at  temperatures  below  the  boiling-point  noth- 
ing will  happen.  For  this  reason  the  pressure  on  the  lower 
side  must  be  such  that  the  boiling  temperature  is  below  the 
temperature  of  the  body  from  which  it  is  to  abstract  heat,  and 
when  evaporated,  the  pressure  must  be  raised  to  a  point  at 
which  the  boiling  temperature  will  be  above  that  of  the  substances 
used  to  abstract  heat.  In  this  latter  condition  the  substances 
will  abstract  heat  from  the  vapor  and  condense  it. 

These  methods  have  been  used  for  years  to  obtain  cool 
water,  to  preserve  foods  and  for  other  purposes.  In  many 
places,  however,  this  preservation  was  carried  on  by  the  use 
of  natural  ice  harvested  in  the  winter  and  stored  until  needed 
in  warm  weather. 


4  ELEMENTS  OF  REFRIGERATION 

It  was  about  the  middle  of  the  last  century  that  the  Carre 
Brothers  produced  commercial  machines  for  the  freezing  of 
water.  Both  machines  operated  to  remove  heat  by  vapor- 
ization of  a  volatile  fluid,  Edmund  Carre  evaporating  water 
vapor  at  very  low  pressures  and  Ferdinand  Carre  evaporating 
liquid  anhydrous  ammonia.  These  machines  were ,  not  used 
to  produce  large  quantities  of  ice,  but  they  produced  com- 
mercial quantities. 

The  compression  type  of  machine  introduced  in  1835  by 
Perkins  was  further  developed  by  Twining,  who  took  out  his 
English  patent  in  1850  and  his  U.  S.  patent  in  1853.  In  this 
machine  a  volatile  liquid  such  as  ether,  carbon  disulphide  or 
sulphur  dioxide  is  allowed  to  flow  through  a  throttle  valve  into 
a  region  of  such  low  pressure  that  the  boiling  temperature  of 
the  liquid  is  low.  This  liquid  will  boil  by  the  .abstraction  of 
heat  from  the  substance  around  the  walls  of  the  chamber  in 
which  it  is  placed.  The  pressure  is  maintained  at  a  low  point 
by  the  suction  of  a  compressor  which  removes  the  vapor  as  it 
is  formed  and  compresses  it  to  a  higher  pressure.  This  pressure 
is  high  enough  to  give  a  temperature  of  boiling  or  liquefaction 
higher  than  that  of  a  water  supply.  The  water  will  remove 
heat  from  the  vapor  and  cause  its  liquefaction.  The  liquid 
is  then  passed  through  the  cycle  again.  In  this  system  the 
liquid  and  its  vapor  are  kept  separate  from  everything  else  by 
being  contained  in  a  closed  system.  Such  a  machine  produced 
commercial  quantities  of  ice. 

There  is  one  other  method  of  abstracting  heat,  which  has 
been  used  for  some  time.  This  is  the  compressed-air  method. 
If  air  is  compressed  rapidly,  its  temperature  is  increased,  due  to 
the  work  which  has  been  done  upon  it.  This  air  may  be  cooled 
to  its  original  temperature  by  being  passed  through  pipes 
over  which  water  is  allowed  to  flow,  and  if  this  high-pressure 
air  is  permitted  to  drive  a  piston  and  do  work,  the  work  done 
will  cause  a  decrease  in~temperature,  so  that  the  expanded 
air  will  be  so  cold  that  it  will  abstract  heat  from  a  space  or 
room  through  which  it  may  be  passed  in  pipes  or  in  the  open 
on  its  way  to  the  suction  of  the  compressor.  In  this  case 


PHYSICAL  PHENOMENA  AND  INTRODUCTION  5 

the  heat  abstracted  in  the  refrigerator  and  that  equal  to  the 
difference  between  the  works  of  the  compressor  and  of  the 
expander  are  taken  up  by  the  cooling  water.  In  this  machine 
the  compressor  and  expander  work  on  the  same  shaft. 

In  all  mechanical  refrigerating  machines  the  working  sub- 
stance is  placed  in  such  a  condition  that  it  will  abstract  heat 
from  the  material  of  low  temperature  and  after  this  absorption 
it  is  placed  in  such  a  condition  that  it  will  give  up  this  heat 
and  that  added  to  operate  the  process,  to  a  water  supply 
at  a  higher  temperature  than  that  of  the  refrigerator  space. 
This  is  the  general  principle  of  all  refrigerating  machines. 

In  the  middle  of  the  last  century  a  development  of  the 
western  part  of  the  United  States  took  place,  and  with  it  arose 
a  desire  to  ship  fruits  from  the  central  parts  of  the  country  to 
the  East.  In  1866  refrigerated  boxes  holding  200  quart  baskets 
of  strawberries  and  100  Ibs.  of  ice  were  built.  These  weighed 
complete  600  Ibs.  They  proved  that  fruit  could  be  shipped 
if  kept  cool.  This  was  done  by  Parker  Earle.  In  1868  Davis 
of  Detroit  proposed  to  insulate  cars  to  handle  beef  and  fish, 
and  in  1872  there  were  successful  experiments.  This  was  the 
beginning  of  the  refrigerated  car  industry,  which  has  so  extended 
that  in  1910  there  were  over  130,000  cars  in  the  United  States, 
although  only  a  little  over  1000  in  Europe. 

The  original  refrigeration  and  even  a  large  amount  of  modern 
refrigeration  have  been  accomplished  by  ice.  The  machines 
for  the  manufacture  of  .the  so-called  artificial  ice,  or  better 
manufactured  ice,  have  made  possible  the  refrigerating  of  stores 
or  other  houses  by  the  use  of  this  apparatus  without  the  em- 
ployment of  ice.  In  these  cold-storage  warehouses  the  vol- 
atile liquid  may  be  passed  through  pipes  in  the  various  rooms, 
from  which  it  abstracts  heat  and  vaporizes,  or  the  evaporation 
of  the  liquid  may  abstract  heat  from  a  strong  brine  of  a  very 
low  freezing-point.  This  cold  brine  is  pumped  through  the 
rooms,  removing  heat.  This  latter  method  is  spoken  of  as  the 
cool-brine  system  of  refrigeration,  while  the  former  is  called 
the  direct-expansion  system.  The  method  of  mechanical  refrig- 
eration has  made  it  possible  to  care  for  storage  in  warm  countries 


6  ELEMENTS  OF  REFRIGERATION 

at  a  distance  from  ice  fields.  It  has  permitted  the  refrig- 
eration of  certain  portions  of  vessels  during  long  voyages.  It 
has  also  led  to  the  possibility  of  the  cold  storage  of  food 
products.  In  1905  it  was  stated  that  the  value  of  food  prod- 
ucts in  cold  storage  in  the  United  States  amounted  to  over 
$200,000,000,  and  the  investment  in  refrigerating  apparatus 
amounted  to  over  $100,000,000. 

The  first  long-distance  shipment  of  meats  in  refrigerators 
on  shipboard  was  in  1873,  but  it  was  unsuccessful.  In  1875 
successful  shipments  were  made  from  America  to  England, 
and  in  1880  Australia  shipped  meat  to  England.  These  ship- 
ments have  so  grown  that  in  1910  the  United  Kingdom  im- 
ported nearly  13,000,000  carcasses  of  lamb  and  mutton  and 
over  4,000,000  quarters  of  beef  from  South  America,  New  Zealand 
and  Australia.  In  1904  the  United  Kingdom  paid  $45,000,000 
for  fruit,  of  which  one-ninth  came  from  the  United  States. 
In  1910  there  were  more  than  800  vessels  equipped  for  the 
transportation  of  food  products  in  cold  storage. 

From  the  above  the  original  importance  of  this  mechanical 
refrigeration  is  seen,  but  with  its  development  further  applica- 
tions have  been  made  and  at  the  present  time  its  use  enters 
into  many  industries. 

Cut  flowers  are  kept  for  a  considerable  time,  and  even  trees 
may  be  held  dormant  for  weeks  to  prevent  budding  before  trans- 
planting in  the  spring.  Milk  and  cream  may  be  kept  sweet  for 
some  time  by  means  of  refrigeration.  In  the  manufacture  of 
wine  and  beer  this  apparatus  is  used  to  prevent  the  rise  of  tem- 
perature as  well  as  to  cool  hot  liquids.  In  the  refining  of  oils 
the  apparatus  is  used  for  the  removal  of  certain  paraffin  products. 
In  the  ventilation  of  buildings  in  warm  weather,  cooled  brine 
may  be  employed  to  cut  down  the  humidity  of  the  air  as  well 
as  the  temperature.  This  is  applied  also  in  metallurgical  oper- 
ations to  remove  the  excess  moisture  from  the  air  entering  a 
blast  furnace,  as  well  as  to  make  the  air  of  uniform  quality. 
In  the  manufacture  of  textiles,  in  the  curing  of  tobacco  and 
in  cigar  making,  in  .the  making  of  perfumery,  in  the  manu- 
facture of  photographic  films  and  other  products,  as  well  as 


PHYSICAL  PHENOMENA  AND  INTRODUCTION  7 

in  developing,  the  use  of  the  refrigerating  machine  or  its  product 
is  indispensable.  Even  in  mining  and  in  excavating  the  re- 
frigerating machine  has  been  applied :  in  the  first  case  to  cool 
warm  excavations,  and  in  the  second  to  freeze  a  ring  of  quick- 
sand so  that  an  excavation  could  be  made  through  this  treacher- 
ous material.  In  therapeutics,  the  value  of  refrigeration  is  being 
seen.  Mr.  W.  T.  Robinson  has  stated  that  he  has  known  of 
hay  fever  patients  being  relieved  by  visiting  cold-storage  ware- 
houses. 


CHAPTER  II 

METHODS   OF  REFRIGERATION 

THE  commercial  methods  of  refrigeration  or  the  cooling 
of  materials  and  spaces  are  as  follows : 

1.  Natural  ice; 

2.  Air  machines; 

3.  Compression  machines  using  volatile  liquids; 

4.  Absorption  machines  using  volatile  liquids; 

5.  Evaporation; 

6.  Chemical  methods. 

In  describing  these  methods  and  in  illustrating  them,  the 
endeavor  has  been  made  to  show  certain  well-known  types  of 
apparatus  so  that  the  student  may  study  actual  forms  of 
machines.  The  peculiarities  of  the  apparatus  must  be  noted 
and  studied  in  the  examples  chosen,  since  these  are  found 
in  most  apparatus  for  this  purpose.  The  examples  taken  are 
those  known  to  the  author,  and  represent  good  practice.  There 
are  many  machines  built  of  value  equal  to  that  of  those  shown, 
and  in  buying  machinery  comparison  must  be  made  between 
all  parts  before  deciding  which  machine  is  the  best. 

In  the  application  of  natural  ice,  which  is  that  employed 
in  the  common  refrigerator,  the  ice  is  used  to  cool  the  air  in 
contact  with  it,  and  then  this  air,  becoming  heavy,  drops  to 
the  bottom  of  the  refrigerated  space,  displacing  warmer  air, 
which  rises  to  the  ice  chamber,  where  it  is  cooled  by  the  melt- 
ing of  a  proper  amount  of  ice.  Fig.  i  illustrates  the  form 
of  refrigerator  built  by  the  McCray  Company.  The  ice  is 
introduced  on  one  side  of  the  ice  box  and  the  air  is  circulated 
downward  to  the  lower  part  of  that  side,  rising  to  the  provision 
side  of  the  refrigerator.  The  walls  of  the  refrigerator  are 


METHODS  OF  REFRIGERATION 


made  of  several  thicknesses  of  materials.  As  shown,  it  con- 
sists of  oak,  sheathing  paper,  poplar  or  some  other  lumber, 
sheathing  paper,  mineral  wool,  sheathing  paper,  lumber,  felt 
and  opal  glass,  nine  layers  in  all.  This  makes  a  well-insulated 
box. 

In  Fig.  2  the  Jackson  system  of  cold  storage  is  shown.     In 


r^ --'--•    ••  ;" 


Oak 
-»Paper 

Poplar 
-"Paper 

Mineral  Wool 

Paper 
-*-Poplar 

Felt 

Opal  Glass 


FIG.  i. — McCray  Refrigerator. 

this  the  cold  air  falls  around  the  ice  and  drops  into  the  cold- 
storage  room,  after  which,  on  being  heated,  it  ascends  to  the 
ice  room.  The  ice  is  supported  on  a  slat  floor  and  the  drip  is 
caught  in  the  necessary  pans,  from  which  it  is  removed  by 
pipes.  The  columns  are  properly  protected  against  this  drip. 
The  air  leaving  the  ice  chest  is  saturated  with  moisture  at  the 
temperature  of  the  ice,  and  as  it  descends  into  the  warmer 
portions  of  the  box  its  moisture  capacity  is  increased,  so  that 


10 


ELEMENTS  OF  REFRIGERATION 


there  will  not  be  any  deposit  of  moisture  from  the  air.  As 
the  air  passes  over  the  goods,  there  is,  if  anything,  a  tendency 
to  take  up  moisture,  and  when  the  air  enters  the  ice  chest  this 


Lumber        Paper      Lumber 


Bricks 

Pitch  or  other 
Water  Proofing 
Saw  Dust  between 

studds 
Lumber 
Paper 
Lumber 
Air  Space 
Lumber 
Paper 
Lumber 


Dement  Concrete 
^Pitch  Water  Proofing 
Cork  Board 
Pitch 
Cork  Board 


FIG.  2. — Jackson  System  of  Cold  Storage. 

moisture  is  removed  as  the  temperature  falls.  This  means 
additional  ice  melting.  This  is  not  a  loss,  as  the  evaporation 
in  'the  box  abstracts  heat  and  this  increases  the  cooling  effect 
at  this  point,  for  which,  of  course,  ice  is  melted  later.  The 


METHODS  OF  REFRIGERATION 


11 


methods  of  insulating  floors,  walls,  and  ceilings  are  to  be  exam- 
ined by  the  student  in  the  figures  shown. 

In  Fig.  3  the  arrangement  of  the  Dexter  system,  in  which 


FIG.  3.— Dexter  System  of  Cold  Storage. 

the  air  from  the  ice  room  does  not  enter  the  cold-storage  room, 
is  shown.  This  drawing  is  self-explanatory.  In  all  these 
arrangements  the  water  from  the  melting  ice  may  be  taken 


12 


ELEMENTS  OF  REFRIGERATION 


METHODS  OF  REFRIGERATION  13 

through  pipes  placed  in  the  cold-storage  room.  This  water 
is  cold  and  will  remove  some  heat  by  being  warmed  to  the 
temperature  of  the  storage  room.  In  this  way  the  apparatus 
is  made  more  efficient.  Fresh  air  for  ventilation  may  be  intro- 
duced by  a  duct  leading  to  the  outside  through  the  ice  room. 

Fig.  4  illustrates  the  method  of  cooling  refrigerator  cars. 
In  these  ice  is  introduced  at  each  end  of  the  car,  and  the  cir- 
culation of  air,  in  at  the  top  and  out  at  the  bottom,  cools  the 
air  and  maintains  a  low  temperature.  The  refrigerator  car 
shown  has  been  recently  built  by  the  American  Car  and  Foundry 
Co.  for  the  Illinois  Central  R.  R.  for  their  express  service.  The 
cars  are  50  ft.  long  and  have  a  capacity  of  40  tons.  They  weigh 
75,700  Ibs.  each.  They  are  supported  on  steel  frames.  The 
car  proper  is  built  of  yellow-pine  framing  supported  on  steel 
under-framing.  The  insulation  is  made  up  of  lumber,  insulating 
material  and  spaces  arranged  as  shown  in  the  figure.  The 
door  section  is  shown  on  the  right  of  the  cross-section  as  well 
as  the  ice  chute  on  the  left.  The  ice  is  packed  in  collapsible 
compartments  at  each  end  of  the  car,  and  rests  on  a  rack  or 
support  at  the  bottom.  This  is  the  Bohn  Collapsible  ice  box. 
From  it  the  air  is  deflected  by  curved  slats  into  the  refrig- 
erated space.  It  passes  through  a  screen  to  prevent  the  en- 
trance of  solid  bodies.  The  rack  at  the  bottom  folds  up  into 
the  end  of  the  car  and  the  slatted  front  folds  up  to  the  roof. 
The  end  of  the  car  is  protected  from  the  ice  by  the  horizontal 
strips  shown  in  the  cross-section.  Ice  is  charged  through  the 
upper  doors.  Sometimes  the  ice  is  broken  in  a  crusher  before 
being  introduced  and  sometimes  ice  blocks  are  used.  The  space 
for  ice  is  about  3  ft.  long,  6|  ft.  from  ice  support  to  roof,  and 
8  ft.  wide.  This  would  hold  about  3  tons  of  ice  at  each  end. 
There  is  an  insulating  plug  in  each  of  the  four  ice  hatches, 
and  the  covers  are:equipped  with  adjustable  latches  to  give  ven- 
tilation when  needed.  The  water  is  drained  from  the  bottom. 

In  the  above  installations,  temperatures  of  36°  to  38°  may 
be  obtained  in  warm  weather.  When  lower  temperatures  are 
desired,  resort  must  be  made  to  mixtures  of  salt  and  ice.  The 
following  table,  given  by  T.  Bowen  in  Bulletin  98,  U.  S.  De- 


14 


ELEMENTS  OF  REFRIGERATION 


partment  of  Agriculture,  gives  the  temperature  resulting  from 
mixtures  of  ice  and  salt: 


Per  cent  salt  in  mixture  by  weight . .   o  5 

Temperature  of  mixture 32         27 


10  15  20  25 

20  II  I.S        —10 


Heat  of  Solution,  B.t.u.per  Lb.  of  Salt. 

S  g  g  £  g  8 

\ 

\ 

\ 

\ 

X 

X 

\ 

X 

^ 

~^- 

^ 

~--~. 

-  — 

151°  20$  25$ 

Weight  of  Salt  as  a  i  of  Ice  used 


:x* 


JTIG.  5. —Curve  of  Heat  of  Fusion  of  One  Pound  of  Salt  for  Different  Amounts 
of  Salt.     (J.  T.  Bowen.) 

The  heat  of  solution  of  the  salt  varies  from  58  B.t.u.  to 
1 6  B.t.u.,  depending  on  the  concentration  of  the  salt.  On 
melting  the  ice,  which  requires  143.4  B.t.u.,  and  dissolving 
the  salt,  which  requires  a  variable  amount,  the  total  heat 
required  will  be  the  sum  of  that  due  to  the  salt  solution  and  the 
melting  of  the  ice. 


METHODS  OF  REFRIGERATION 


15 


For  different  percentages  of  salt  added  to  water  the  heat 
of  solution  is  given  by  the  curve  of  Fig.  5.  Since  the  heat 
of  solution  of  salt  is  less  than  that  of  ice,  the  heat  of 
melting  of  a  mixture  of  ice  and  salt  per  pound  of  mixture 


1KA 

"3 

\ 

^. 

3 

^^ 

^ 

5 

\ 

^^ 

3 
Jj 

% 

.. 

^^ 

s^ 

§      " 
O 

~^ 

k. 

1 

"^ 

•<, 

3  no 

pa 

100 

3>t 


Weight  of  Bait  as  a  Percentage  of  the  Ice  used. 


FIG.  6. — Heat  of  Melting  One  Pound  of  Ice  and  Salt  in  Different  Proportions. 

(J,  T,  Bowen.) 

decreases  as  the  amount  of  salt  increases.     This  is  shown  in 
Fig.  6. 

The  specific  heat  of  the  salt  brine  and  of  ice  must  be  known 
to  make  the  necessary  calculations  for  the  heat  removed  and 
the  temperature  of  the  mixtures.  The  specific  heat  of  the 
brine  for  different  percentages  of  salt  is  given  in  Fig.  7. 


16  ELEMENTS  OF  REFRIGERATION 

The  specific  heat  of  ice  at  absolute  temperature  T,  is  given  by 

c  =  0.5057+0.001863^^-^-, 
as  determined  by  Dickinson  and  Osborne. 


Specific  Heat  of  Salt  Briae. 

>  P  P  P  f 
3  3  §  8  8 

^^ 

^X 

X 

s^ 

^ 

-  —  — 

^  — 

•^^^^ 

, 

-—  ~-_ 

1  ^ 

~^- 

*-^. 

^  — 

0.50 

Hty  15^  20^fc  25$ 

Salt  iis  a  Percoiitagc  of  the  Water  used. 


30$ 


35^ 


FlG<  7._Specific  Heat  of  Salt  Brine  for  Different  Amounts  of  Salt.)     (Bowen.) 

By  mixing  ice  and  salt  together  low  temperatures  may  be 
obtained  for  chilling  or  freezing.  The  ice  must  be  brought 
into  intimate  contact  with  the  salt,  and  for  that  reason  the 
ice  is  broken  into  small  pieces.  This  of  course  necessitates 
the  ice  filling  a  containing  vessel,  which  is  placed  in  the  storage 
room;  although  in  some  cases  air  is  drawn  through  the  mix- 


METHODS  OF  REFRIGERATION 


17 


ture.     This  is  difficult,  as  the  mixture  sometimes  freezes  into 
a    solid    mass.     Then    it   becomes   necessary    to   increase    the 


FIG.  8. — Diagram  of  Cooper  Gravity  Brine  Circulating  System. 

surface  used  to  refrigerate  the  room.     Certain  patented  methods 
have  been  proposed. 


18  ELEMENTS   OF  REFRIGERATION 

The  Cooper  gravity  brine  circulation  system  is  shown 
diagrammatically  in  Fig.  8.  In  this  ice  is  broken  in  a  crusher 
and  delivered  to  the  top  of  the  storage  house,  or  it  may  be 
crushed  at  the  top  after  it  is  delivered.  Here  it  is  mixed 
with  salt  and  introduced  into  the  ice  tank. 

This  tank  contains  a  set  of  coils  filled  with  brine,  and  con- 
sequently the  mixture  of  ice  and  salt  removes  heat  from  the 
brine,  cooling  it  to  the  temperature  of  the  mixture.  After 
this  is  done  there  will  be  no  further  melting  except  that  due 
to  the  heat  loss  from  the  tank.  When,  howeVer,  the  valves 
controlling  the  brine  system  are  opened,  the  heavy  cold  brine 
will  tend  to  fall  to  the  lowest  part  of  the  system,  bringing 
warm  brine  to  the  top  and  producing  a  strong  circulation. 
The  brine  then  removes  heat  from  the  refrigerator  rooms, 
being  passed  through  coils  on  the  walls  or  ceiling.  The  ice  tanks 
are  about  10  ft.  high.  The  lower  part  is  not  very  active,  as 
the  brine  in  the  coils  is  cooled  by  the  time  it  reaches  this 
point,  and  the  salt  brine  from  the  melting  ice  cannot  take  up 
any  more  salt,  as  its  temperature  is  too  low.  The  ice  and 
salt  must  be  thoroughly  mixed  before  introduction,  as  the 
salt  is  apt  to  cake.  When  a  new  charge  is  to  be  introduced, 
the  ice  in  the  tank  should  be  stirred  with  a  stick  to  prevent 
any  caking.  The  brine  formed  from  the  ice  melting  is  of 
value  for  cooling  in  that  it  is  at  a  low  temperature.  It  may 
be  passed  through  the  refrigerated  rooms  in  pipes,  or  it  may 
be  used  at  other  points.  Cooper  claims  that  two  men  can 
handle  4  tons  of  ice  per  hour  in  charging  this  system  and 
that  4  tons  per  day  will  cool  a  storehouse  of  40  cars  capacity 
in  average  summer  weather.  The  amount  required  in  any 
case  may  be  computed  from  the  heat  losses  in  the  storage 
house. 

Air  machines  are  operated  in  the  following  manner:  Air 
is  compressed  in  a  cylinder  A  from  a  pressure  pi  to  a  pressure 
p2.  The  air  is  discharged  from  the  compressor  through  a  set 
of  self-acting  mushroom  valves  or  by  a  slide  valve,  and  is 
passed  into  cooling  coil  B,  which  is  surrounded  by  water.  In 
this  coil  the  air  which  has  been  heated  by  the  compressor  is 


METHODS  OF  REFRIGERATION 


19 


cooled  almost  to  the  temperature  of  the  water,  and  by  this 
cooling  it  is  reduced  in  volume  and  is  passed  into  the  expansion 
cylinder  C  This  is  mounted  in  tandem  with  the  compressor, 
as  in  the  Lightfoot  machine,  or  beside  the  compressor  attached 
to  the  same  shaft  as  in  the  Allen  Dense  Air  machine.  The 
air-expansion  cylinder  is  arranged  in  the  same  manner  as  the 
cylinder  of  a  steam  engine.  It  has  a  slide  valve  or  valve  gear, 
which  cuts  off  the  air  supply  at  the  proper  point  and  permits 
expansion  to  occur.  This  expansion  should  be  complete  (re- 


FIG.  9. — Closed  and  Open  Air  Refrigerating  Machines. 

duced  to  back  pressure  at  the  end  of  expansion).  This  is 
accomplished  by  having  the  cut  off  occur  at  the  proper  point. 
^  As  this  air  expands,  doing  work  at  the  expense  of  its  intrinsic 
energy,  its  temperature  is  decreased  so  that  when  the  exhaust 
pressure  is  reached  the  air  may  be  at  some  temperature  between 
—  50°  F.  and  -100°  F.  The  temperature  is  fixed  by  the 
amount  of  expansion.  This  cold  air  is  now  discharged  into 
a  coil  D  or  a  room  £,  and  it  removes  much  heat  before  it  is 
brought  up  to  the  temperature  at  which  it  enters  the  com- 
pressor cylinder  to  repeat  the  cycle. 

The  system  on-  tHe  left  is  known  as  a  closed  system,  while 


20 


ELEMENTS  OF  REFRIGERATION 


that  on  the  right  in  which  the  air  is  discharged  into  the  room 
E  is  known  as  an  open  system. 

The  air  occupying  less  volume  in  the  air  expander  than 
it  does  in  the  compressor  on  account  of  lower  temperature, 
means  that  there  will  be  less  work  returned  by  the  expander 
than  that  required  by  the  compressor;  hence  power  must  be 
supplied  by  an  external  motor  of  some  form. 

This  may  be  a  steam  engine  as  at  F,  Fig.  9,  or  an  electric 
motor  may  be  applied. 

To  show  the  work  done  by  indicator  cards  the  compressor 


7-1 


FIG.  10. — Cards  from  Air  Refrigerating  Machines. 

and  expander  cards  are  shown  in  Fig.  10,  assuming  zero  clear- 
ance. This  may  be  assumed,  since  clearance  does  not  affect 
the  work  of  a  card.  These  cards  may  be  superimposed  and 
the  area  2356  shows  the  net  work  which  must  be  supplied 
if  friction  be  disregarded.  This  is  the  work  that  the  motor 
must  supply.  The  real  work,  of  course,  if  /  is  the  percentage 
friction,  is 

,          /lOO+A  /lOO-A 

Network=l-    — —  1  area  1 234  —  (  -    — ^- ) area  4567. 
\    100    /  \    100    / 


METHODS  OF  REFRIGERATION  21 

In  this  machine,  air,  by  compression,  is  put  into  such  a  \ 
condition  that  the  water  supply  will  abstract  heat  and  then,  by* 
expansion,  it  is  put  into  such  a  condition  that  it  will  abstract^ 
heat  from  a  place  of  low  temperature. 

The  advantages  claimed  for  these  machines  are:  the  use 
of  no  chemical  which  might  lead  to  explosions  or  loss  of  life 
due  to  accidental  escape  of  gas;  the  possibility  of  very  low 
temperatures;  simple  construction  and  the  accessibility  of 
all  parts. 

The  first  air  machine  was  designed  by  Gorrie  in  1849.  Kirk 
designed  one  in  1863.  In  1877  the  Bell-Coleman  improvements 
made  the  machine  practical,  and  the  application  of  this  machine 
to  ocean  steamships  made  possible  the  cold-storage  shipments 
of  meat.  The  machine  was  improved  by  a  number  of  later 
inventors. 

There  are  few  air  machines  used  to-day,  owing  to  the  greater 
efficiency  of  types  of  apparatus  using  other  working  substances. 
But  efficiency  is  not  always  the  criterion  by  which  to  judge 
of  the  advisability  of  using  a  certain  form  of  machine.  Reli- 
ability, ease  of  operation,  small  maintenance  cost,  and  absence  of 
poisonous  substances  may  be  important  factors  to  consider  in 
making  a  selection.  For  such  reasons  air  machines  are  still 
in  use.  One  of  the  most  common  forms  of  air  machines  used 
in  the  United  States  is  the  Allen  Dense  Air  Machine,  shown 
in  Fig.  n.  In  this  the  three  cylinders,  steam,  compressor 
and  expander,  are  placed  beside  each  other,  and  are  connected 
to  three  cranks  of  a  common  shaft.  The  cylinder  A  in  the 
front  of  the  figure  is  the  expansion  cylinder,  the  second  is  the 
compressor  cylinder,  and  the  back  cylinder  is  that  of  the  steam 
engine.  Between  the  compressor  and  expander  is  seen  the 
plunger  of  a  small  air  pump  used  to  maintain  the  air  pressure 
in  the  system  and  make  up  for  any  leaks.  This  is  driven 
by  an  extension  from  the  cross-head  of  the  compressor.  A 
similar  extension  on  the  other  side  of  this  cross-head  drives 
a  plunger  of  the  circulating  pump  which  forces  water  through 
the  cooling  chamber  B  placed  on  top  of  the  machine.  Two 
eccentrics  on  the  shaft  control  the  various  valves.  The  pipe 


22 


ELEMENTS  OF  REFRIGERATION 


C  takes  the  cool  compressed  air  from  the  coils  in  the  water- 
cooler  to  the  expansion  cylinder  A,  and  after  expanding,  the 


air  is  passed   through  pipe  D   to   the  refrigerator,  and   then 
returned  to  the  compressor  through  E. 


METHODS   OF  REFRIGERATION 


23 


This   apparatus  is  known   as   a   dense   air  machine.     The 
air  is  at  60  to  70  Ibs.  gauge  pressure  on  the  low-pressure  side, 


the  high  pressure  ranging  from  210  to  240  Ibs.  As  will  be 
seen  later,  the  refrigerating  effect  is  due  to  the  ratio  of  these 
two  pressures  and  not  to  the  absolute  value  of  each.  By 
using  a  high  pressure  on  the  lower  side,  the  displacement  of 


24  ELEMENTS  OF  REFRIGERATION 

the  cylinders  for  a  given  amount  of  refrigeration  is  materially 
decreased. 

The  diagrammatic  arrangement  of  the  machine  is  shown 
by  'the  maker,  H.  B.  Roelker  (Leicester  Allen,  1879,  inventor) 
in  Fig.  12.  F  is  the  compressor  cylinder,  in  which  a  special 
pair  of  valves,  driven  by  eccentrics  G  and  H  through  rock 
shafts,  give  ample  outlet  area  at  the  proper  time.  The  com- 
pressed air  is  then  passed  through  the  copper  coil  /,  placed 
in  the  water-cooler  B,  where  it  is  cooled  down  almost  to  the 
temperature  of  the  water  entering  at  /  from  the  pump  K. 
The  pump  is  driven  from  the  cross-head  of  the  compressor. 
The  water  used  in  the  cooler  passes  through  the  jacket  of  the 
compressor  before  being  discharged.  The  cooled  air  passes 
through  the  pipe  C  to  the  expander  At  which  is  controlled 
by  a  riding  cut-off  valve  gear  as  shown.  After  expansion  the 
cold  air  leaves  by  D  and  passes  through  an  oil  and  snow  trap 
L,  entering  an  ice-making  box  M,  or  that  part  of  the  system 
in  which  the  lowest  temperature  is  required.  The  ice  box 
may  be  a  steel  brine  tank  containing  coils  for  the  passage  of 
the  air,  or  it  may  be  a  double-walled  casting  containing  cells 
for  the  ice-making  cans.  These  cells  are  supplied  with  brine 
to  fill  the  space  between  the  casting  and  can,  thus  conducting 
heat  from  the  can  to  the  air  at  a  higher  rate  than  that  at  which 
it  would  otherwise  pass  through  an  air  space.  The  hollow 
part  of  the  casting  is  that  through  which  the  air  passes.  The 
air  is  next  conducted  to  the  refrigerating  room,  where  the 
temperature  need  not  be  so  low  as  that  required  to  make  ice. 
If  a  low  temperature  is  desired  in  a  room,  some  of  the  low-tem- 
perature air  will  have  to  be  taken  directly  to  that  room.  The 
air  is  distributed  through  the  room  in  coils  of  pipe  N  and  then 
is  taken  to  a  water  butt,  where  it  cools  drinking  water  to  40° 
F.  or  50°  F.  The  air  is  then  returned  to  the  compressor  through 
the  pipe  E.  If  the  air  is  still  at  a  low  temperature,  it  is  some- 
times passed  around  the  pipe  C,  and  this  cools  the  air  going 
to  the  expander  so  much  that  a  very  low  temperature  is  ob- 
tained. The  pump  0  is  the  air-charging  pump  driven  from 
the  cross-head  of  the  compressor.  This  pump  draws  air  through 


METHODS   OF  REFRIGERATION  25 

its  plunger,  and  after  compression  the  air  is  delivered  to  the 
trap  P,  which  is  surrounded  by  cold  water.  This  cools  the  air 
and  causes  a  large  part  of  the  moisture  brought  in  from  the 
atmosphere  to  be  separated  and  drained  off.  This  air  is  then 
delivered  to  the  pipe  E  and  is  mixed  with  the  air  going  to 
the  compressor.  The  valves  Q  and  R  cut  off  the  low-temper- 
ature parts  when  it  is  desired  to  operate  the  by-pass  5.  The 
valve  T  allows  hot  air  to  enter  the  expander  from  the  com- 
pressor and  thus  pass  into  the  trap  L,  removing  grease  and  snow 
from  it.  The  trap  or  separator  L  has  a  double  bottom  or  steam 
jacket  which  may  be  used  to  melt  any  congealed  oil  or  water, 
and  so  open  up  the  line  if  closed. 

To  start  this  machine,  the  blow-valve  on  the  expander 
and  petcocks  on  the  traps  are  kept  open  until  no  more  grease 
passes  through.  Then  the  valves  Q  and  R  are  opened  and  S 
closed.  After  this  T  is  closed.  The  circulating  water  is  then 
turned  on,  and  gradually  the  low-pressure  side  should  be 
charged  by  0  until  a  pressure  of  60  Ibs.  is  reached.  The  high- 
pressure  will  then  be  210  Ibs.  The  petcock  on  the  water  trap 
P  should  be  opened  to  keep  the  water  level  below  the  half-full 
point.  The  stuffing-boxes,  which  contain  three  or  four  metallic 
rings,  an  oiling  ring  and  three  or  four  rings  of  soft  packing, 
should  be  supplied  with  oil.  This  oil  keeps  the  packing  tight 
with  little  tightening  of  the  gland,  and  consequently  little' 
friction.  These  stuffing-boxes  are  placed  at  places  where  the 
greatest  loss  of  air  occurs.  The  sight-feed  lubricators  are  con- 
nected to  the  stuffing-boxes.  The  air  pistons  are  packed  with 
cup  leathers  which  last  about  two  months  for  steady  work. 
They  are  made  of  f  in.  thickness  and  are  kept  flexible 
by  soaking  in  castor  oil.  Once  or  twice  a  day  the  machine 
is  cleaned  of  oil  and  grease  by  opening  S  and  closing  Q  and 
R,  ana  then  opening  T,  T'  and  T" .  After  this,  steam  is  passed 
into  the  jacket  of  L  and  the  petcock  is  opened.  A  blow-off 
from  the  expander  is  also  opened.  This  is  done  for  about 
one-half  hour.  A  change  in  the  ratio  of  the  two  pressures  is 
due  to  leaky  pistons,  while  a  drop  in  the  low  pressure  is  due  to 
leaky  stuffing-boxes.  These  machines  are  made  in  small  sizes: 


26 


ELEMENTS  OF  REFRIGERATION 


the  largest  are  of  3  to  4  tons  capacity.  They  are  used  chiefly 
for  marine  work.  There  are  a  number  of  foreign  air  refriger- 
ating machines.  Such  firms  as  Haslam  &  Co.,  J.  &  E.  Hall, 
and  I.  &  W.  Cole  are  engaged  in  making  these.  They  vary 
only  in  the  matter  of  details  from  the  machine  just  outlined, 
and  for  that  reason  these  will  not  be  described. 

The  system  of  refrigeration  using  a  volatile  liquid  is  shown 
in  Fig.  13.  To  be  a  little  more  definite,  assume  that  anhydrous 
ammonia  is  used  as  the  working  substance.  The  compressor 
A  relieves  the  pressure  in  the  coil  B  by  drawing  vapor  from 


FIG.  13. — Compression  Refrigerating  Machine. 

the  coil,  since  the  coil  is  connected  to  the  suction  side  of  the 
compressor.  The  vapor  thus  removed  is  compressed  by  A 
and  delivered  under  pressure  into  a  condenser  coil  C.  The 
vapor  will  be  compressed  in  C  until  the  pressure  is  such  that 
the  temperature  of  saturated  ammonia  vapor  at  that  pressure 
is  slightly  higher  (about  10°  to  20°)  than  that  of  the  water 
coming  from  the  supply  D.  When  this  pressure  is  reached, 
the  water,  having  a  lower  temperature  than  that  of  saturation 
of  the  ammonia,  will  abstract  heat  from  the  ammonia  and  cause 
it  to  condense  so  that  liquid  ammonia  will  flow  into  the  receiver 
E.  If  now  the  pressure  in  the  coil  B  is  such  that  the  tempera- 


METHODS  OF   REFRIGERATION  27 

ture  of  boiling  for  ammonia  at  that  pressure  is  above  the 
temperature  of  the  substance  around  the  coil  B,  the  ammonia 
gas  and  liquid  in  the  coil  will  give  up  heat  to  the  substance 
through  the  coil  and  will  be  cooled  off,  but  nothing  further 
can  happen.  If,  however,  the  boiling  temperature  corresponding 
to  the  pressure  is  less  than  that  of  the  substances  around  the 
coil  J5,  then  heat  will  flow  from  them  into  the  ammonia  in  the 
coil  and  cause  the  liquid  to  evaporate,  requiring  the  further 
action  of  the  compressor  to  keep  the  pressure  low  enough  to 
remove  heat  from  the  substances  near  the  pipe.  Of  course,  if  the 
first  condition  were  true,  no  vapor  would  form  and  the  action 
of  the  compressor  would  reduce  the  pressure  so  that  the  boiling 
temperature  would  at  least  be  low  enough  to  remove  heat  from 
the  substances.  The  supply  of  liquid  ammonia  is  regulated 
by  the  valve  F,  known  as  an  expansion  valve.  It  is  in  reality 
a  throttle  valve,  throttling  the  liquid  ammonia  from  the  high 
pressure  in  C  to  the  low  pressure  in  B.  The  coil  B  may  be 
placed  in  a  room  to  be  refrigerated  or  it  may  be  placed  in  a 
tank  G,  containing  brine  of  a  low  freezing-point.  This  brine 
is  cooled  and  sent  out  to  rooms  which  are  to  be  refrigerated, 
or  to  ice  tanks,  and  after  receiving  the  heat,  the  warm  brine 
is  returned  to  the  tank  to  be  cooled  again.  The  first  system 
is  known  as  the  direct-expansion  system,  while  the  latter  is 
called  the  brine  system  of  refrigeration. 

The  various  types  of  compressors  used  will  be  described 
in  a  later  chapter.  At  this  point,  however,  one  form  of  com- 
pressor will  be  shown  in  Fig.  14.  This  is  a  steam-driven  com- 
pressor of  the  Frick  Co. 

A  Corliss  steam  cylinder  A  drives  a  shaft  B  with  two 
cranks.  To  the  steam-engine  crank  is  connected  the  rod  of 
one  ammonia  compressor,  while  on  the  other  crank  at  180° 
is  attached  the  connecting  rod  of  the  other  compressor.  Thus 
one  steam  piston  operates  two  ammonia  pistons.  In  some 
cases  the  crank  to  which  the  two  connecting  rods  are  attached 
is  of  the  center  type;  three  bearings  are  then  used.  This 
compressor  is  single-acting.  Low-pressure  ammonia  enters  at 
C  and  passes  into  the  cylinder  on  the  up-stroke  of  the  piston 


28 


ELEMENTS  OF  REFRIGERATION 


D.  The  long  stuffing-box  E  is  quite  a  common  feature  of  all 
compressors,  as  is  the  long  piston  with  a  number  of  piston 
rings.  These  are  necessary  to  prevent  the  escape  of  ammonia, 


ex 

f 


which  is  poisonous  and  expensive.  On  the  down-stroke  of  the 
piston,  the  large  suction  valve  in  the  center  of  the  piston  is  opened 
by  the  vacuum  produced  on  the  upper  side  of  the  piston,  and 
vapor  is  drawn  over  to  that  side.  On  the  return  stroke  of 
the  piston,  the  vapor  is  compressed  in  the  cylinder  until  the 


METHODS  OF  REFRIGERATION  29 

pressure  is  slightly  above  that  in  the  discharge  space  E,  when 
it  opens  the  valve  F  at  the  center  of  the  head  of  the  cylinder. 
This  valve  is  forced  down  by  a  small  spring  so  that  there  is  only 
a  slight  increase  in  pressure  above  the  line  pressure  before 
the  valve  opens.  The  vapor  pressure  in  the  discharge  holds 
it  to  its  seat  on  the  down-stroke  of  the  piston.  The  cylinder 
head  G  is  not  bolted  fast  to  the  cylinder  barrel.  It  is  held 
down  by  the  springs  H  which  press  against  the  main  head  /, 
attached  to  the  barrel.  The  purpose  of  the  safety  compressor 
head  is  to  avoid  the  danger  of  blowing  off  a  head  if  anything 
should  lodge  on  top  of  the  piston.  If  the  suction  or  discharge 
valve  should  break,  or  if  scale  should  accumulate  and  lie  on  top 
of  the  piston,  the  small  clearance  which  exists  in  this  com- 
pressor would  not  be  large  enough  to  care  for  this  material, 
and  with  a  rigid  head  the  cylinder  would  break.  With  the 
safety  head  the  springs  would  yield  and  permit  the  head  to 
lift.  If  for  any  reason  liquid  ammonia  were  to  collect  and 
the  discharge  valve  would  not  relieve  it,  then  the  head  would 
rise.  Around  the  cylinder  is  a  water  jacket  /  for  the  removal 
of  some  of  the  heat  of  compression.  The  value  of  the  jacket 
is  questioned  by  some.  If  too  much  water  is  not  used,  the 
heat  removed  will  not  have  to  be  taken  out  in  the  condenser, 
and  so  nothing  is  lost.  Moreover,  any  heat  removed  during 
compression  decreases  the  work,  so  that  there  is  some  saving 
by  the  judicious  use  of  the  jacket.  If  much  water  is  used, 
there  will  be  a  loss  due  to  the  cost  of  water  being  greater  than 
the  saving  due  to  the  jacket.  K  is  an  indicator  valve  and 
L  is  a  purge  valve  used  to  manipulate  the  compressor. 

The  layout  of  a  plant  using  the  De  La  Vergne  apparatus 
is  shown  in  Fig.  15.  In  this  the  vapor,  or,  as  it  is  usually  called, 
the  gas,  enters  from  the  refrigerating  rooms  or  brine  tank, 
and  passes  to  the  suction  side  of  the  compressor.  This  line 
is  connected  to  the  gauge  board,  where  a  suction  gauge  is  in- 
stalled. This  gauge  is,  of  course,  controlled  by  a  valve  to 
permit  of  its  removal  and  repair.  The  suction  is  sometimes 
connected  to  the  liquid  line  by  an  equalizing  pipe  for  manip- 
ulation of  the  plant.  The  compressed  gas  then  passes  over 


30 


ELEMENTS  OF  REFRIGERATION 


METHODS  OF  REFRIGERATION  31 

to  the  condenser.  This  is  a  coil  of  pipe  made  of  return  bends. 
The  hot  gas  enters  at  the  bottom  and  as  it  passes  upward  it 
is  condensed,  special  bends  being  used  to  remove  the  liquid 
at  different  places.  These  various  drip  lines  are  connected, 
and  finally  the  liquid  is  delivered  to  the  storage  tank  B,  from 
which  it  discharges  through  the  expansion  valve  C  into  the 
expansion  coil  D.  The  various  euqalizing  pipes  serve  to  equalize 
pressures  at  various  points  of  the  system,  so  that  syphonic 
action  may  not  be  set  up.  The  liquid  after  entering  the  re- 
frigerator is  changed  into  vapor  and  returned  to  the  compressor. 
The  passage  through  the  scale  separator  E  removes  the  danger 
of  scoring  the  cylinders.  The  valves^at  the  top  of  the  oil  sep- 
arator A  and  condenser  are  to  rid  the  system  of  non-condensible 
gases  which  collect  there.  These  gases  are  due  to  air  which 
may  be  drawn  in,  or  from  the  oil  which  may  be  decomposed. 
In  some  cases  ammonia  may  be  decomposed.  The  cooling  water 
is  discharged  from  the  pipe  F. 

There  are  other  substances  used  in  compression  systems. 
Sulphur  dioxide,  carbon  dioxide,  and  methyl  chloride  are  the 
common  ones  spoken  of  to-day.  Various  ethers  and  alcohols 
have  been  used  and  certain  mixtures  of  liquids,  such  as  C02 
and  862,  have  been  tried.  On  account  of  cost,  danger  from 
use,  pressures  demanded,  and  sizes  of  parts,  some  prefer  one 
substance  and  some  another.  The  theory  underlying  all  of 
these  is  the  same,  and  the  description  given  above  would  apply 
to  any  of  them.  In  all  machines  the  vapor  is  raised  by  com- 
pression to  such  a  pressure  that  the  water  supply  can  remove 
heat  from  the  vapor  and  condense  it,  and  by  use  of  the  throttle 
valve  it  is  reduced  to  such  a  pressure  that  it  will  remove  heat 
from  a  place  of  low  temperature. 

The  absorption  machine  depends  for  its  action  on  the 
fact  that  for  every  concentration  of  aqua  ammonia,  or  for 
every  per  cent  of  a  solution  of  ammonia  and  water,  which  is 
anhydrous  ammonia,  there  exists  a  certain  temperature-at 
which  the  solution  will  boil  under  a  given  pressure.  Thus, 
if  35%  by  weight  of  a  solution  of  aqua  ammonia  is  NH3,  this 
will  boil  at  227°  F.  under  a  pressure  of  170  Ibs.  gauge,  and  the 


32 


ELEMENTS  OF  REFRIGERATION 


same  solution  will  boil  at  110°  F.  if  under  15  Ibs.  pressure. 
Now  ammonia  under  170  Ibs.  pressure  would  boil  at  91°  F., 
and  at  15  Ibs.  gauge  pressure  it  would  boil  at  o°  F.  If  water 
were  available  at  80°  F.  and  steam  at  235°  F.  or  10  Ibs.  gauge, 
the  following  might  be  done: 

If  the  aqua  ammonia  or  liquor  of  35%  concentration  in  the 
generator  A  be  heated  by  the  steam  at  235°  F.  in  the  steam 
coil  B,  the  solution  will  boil  and  the  ammonia  and  water  vapor 
will  produce  a  gauge  pressure  of  170  Ibs.,  and  this  is  sufficient 
to  have  the  ammonia  condense  in  the  condenser  C  if  water 
at  80°  F.  is  passed  over  the  pipes.  If  the  ammonia  collected 


FIG.  16. — Elementary  Absorption  Machine. 


in  the  receiver  D  is  passed  through  the  throttle  valve  E  into 
the  coil  F,  where  it  may  abstract  heat  from  brine,  it  will  boil 
at  o°  F.,  if  the  pressure  is  maintained  at  15  Ibs.  If  an  aqua 
ammonia  solution  in  the  tank  G,  called  an  absorber,  is  not 
allowed  to  get  above  110°  F.  by  the  cool  water  coil  H,  and  is 
not  allowed  to  get  stronger  than  35%  concentration,  it  will 
absorb  ammonia  and  keep  the  pressure  in  the  absorber  and 
the  line  leading  to  F  at  or  below  15  Ibs.  gauge.  To  keep  the 
solution  in  the  absorber  in  condition  to  absorb  ammonia,  the 
weak  liquor  in  the  generator,  from  which  the  ammonia  was 
removed,  is  allowed  to  flow  into  the  absorber,  the  pump  7 
forcing  the  strong  liquor  from  G  to  A . 


METHODS  OF  REFRIGERATION  33 

This  is  the  explanation  of  the  simple  absorption  machine, 
but  there  are  several  refinements  which  are  used.  Certain 
phenomena  will  have  to  be  described.  When  an  aqua  solution 
boils,  not  only  ammonia  escapes,  but  also  water  vapor.  More- 
over, the  heat  supplied  will  have  to  be  not  only  that  required 
to  drive  off  the  ammonia  (heat  of  solution)  and  that  required 
to  .evaporate  the  moisture,  but  also  enough  to  superheat  the 
ammonia  vapor  and  water  vapor,  since  these  leave  the  gen- 
erator in  a  superheated  condition.  This  excess  of  superheat 
must  be  removed  and  to  reduce  the  amount  of  heat  to  be  taken 
out  by  cooling  water,  and  to  reduce  the  heat  supply  to  the 
generator,  the  cool  strong  solution  coming  from  the  absorber 
is  caused  to  flow  over  trays  through  which  the  heated  gases 
pass  from  the  generator  A.  In  this  way  the  liquor  is  heated 
and  economy  effected.  This  apparatus  is  known  as  the  an- 
alyzer, K. 

The  water  vapor  condensing  in  the  condenser  would  absorb 
some  ammonia  and  reduce  the  efficiency  of  the  apparatus. 
To  reduce  this  loss  it  is  customary  to  pass  the  vapors  leaving 
the  analyzer  through  ]  tubes  L  over  which  the  cool,  weak  solu- 
tion from  the  absorber,  or  water  from  the  condenser,  flows. 
In  this  way  the  temperature  of  the  mixture  of  ammonia  and 
water  vapor  is  so  reduced  that  most  of  the  water  vapor  is 
condensed  and  separated  by  the  separator  M,  and  sent  back 
to  the  analyzer.  L  is  known  as  a  rectifier  or  dehydrator. 
Of  course,  this  water  absorbs  ammonia  and  reduces  the  amount 
sent  to  the  condenser,  but  it  is  not  delivered  to  the  condenser 
and  so  causes  no  trouble.  The  last  change  which  is  introduced 
for  economy  is  to  pass  the  warm,  weak  solution,  which  is  to 
go  to  the  cooled  absorber,  around  pipes  carrying  from  the 
absorber  the  cool,  strong  liquor,  which  has  to  be  heated.  This 
interchange  saves  much  heat.  The  apparatus  is  known  as 
the  interchanger,  /. 

Before  passing  to  the  actual  arrangement,  one  other  point 
must  be  mentioned.  The  solution  is  changed  from  one  con- 
centration to  another  in  the  absorber  and  in  the  generator,  and 
it  must  be  remembered  that  it  is  the  weak  concentration  which 


34 


ELEMENTS  OF  REFRIGERATION 


fixes  conditions  in  the  generator  and  the  strong  concentration, 
those  in  the  absorber. 

The  heat  of  solution  when  aqua  ammonia  changes  from 
one  concentration  to  another  must  be  cared  for  by  the  cooling 
coil  in  the  absorber,  so  that  there  is  no  increase  in  tempera- 
ture, which  would  cut  down  the  possible  concentration.  The 
computations  for  this  system  will  be  given  in  the  next  chapter. 

Fig.  17  shows  the .  absorption  machine  diagrammatically. 
In  this  arrangement  the  strong  solution  in  A  is  boiled  by  the 
steam  in  B.  The  vapor  passes  through  the  analyzer  K,  where 


-   ^     c 

1 

t 

i  ) 

1 

FIG.  17. — Complete  Diagram  of  the  Absorption  Machine. 

it  meets  the  down  current  of  warmed  strong  liquor  coming 
from  the  exchanger  /.  This  cools  the  vapor  and  warms  the 
liquor,  and,  it  may  be,  drives  off  some  ammonia.  The  vapor 
then  passes  to  the  rectifier  or  dehydrator,  L,  which  is  cooled 
by  the  strong  liquor  pumped  by  pump  /  from  the  absorber. 
This  solution  is  cool  enough  to  condense  most  of  the  moisture 
in  the  vapors.  The  water  formed  absorbs  ammonia,  and  this 
liquor  is  removed  by  the  separator  M,  and  is  passed  back 
to  the  analyzer.  The  liquid  from  the  condenser  C  passes  to 
the  receiver  D  and  through  the  valve  E  to  the  expansion  coil 
F,  in  the  brine  tank.  From  the  absorber  G  with  its  cooling 
coil  H  the  liquor  is  pumped  by  7  to  L  and  then  to  the  inter- 


METHODS  OF   REFRIGERATION 


35 


36 


ELEMENTS  OF  REFRIGERATION 


8, 


METHODS  OF  REFRIGERATION  37 

changer  or  exchanger  /,  after  which  it  enters  the  analyzer. 
The  weak  liquor  from  A  passes  through  the  exchanger  /  to  the 
absorber  G. 

Fig.  1 8  illustrates  the  construction  of  an  actual  absorption 
machine  made  by  the  York  Manufacturing  Company.  The 
condenser,  absorber,  and  expansion  coils  are  all  of  the  exposed- 
coil  type.  The  water  lines  going  to  condenser,  deny dra tor, 
and  absorber  are  not  shown.  Purging  valves  are  shown  at 
various  high  points.  They  are  connected  by  purge  lines  which 
are  not  shown.  For  purging  this  system  the  best  location  is  at 
the  absorber,  for  here  all  of  the  ammonia  is  absorbed,  and  the 
gas  remaining  is  true  non-active  gas.  The  various  parts  of 
the  apparatus,  especially  the  expansion  coils,  should  be  purged 
into  the  absorber,  so  that  any  ammonia  coming  over  may  be 
condensed. 

Fig.  19  shows  the  equipment  of  an  absorption  plant  as 
made  by  the  Carbondale  Machine  Co.  This  differs  from  that 
of  Fig.  1 8  in  that  a  double-pipe  condenser  is  used,  instead  of 
an  atmospheric  one;  the  absorber  is  a  tubular  absorber;  the 
weak  liquor  is  cooled  before  entering  the  absorber  and  the 
expansion  coil  is  in  a  brine  cooler.  The  action  of  the  apparatus 
can  be  followed  from  the  description  above. 

The  evaporation  of  a  portion  of  a  body  of  water,  so  as  to 
freeze  the  remaining  portion,  has  been  used  in  a  natural  way 
for  centuries.  One  of  the  first  successful  machines  acting  on 
this  principle  was  made  by  Edmund  Carre  about  the  middle 
of  the  last  century.  The  apparatus  consisted  of  an  air  pump 
attached  to  a  cylindrical  vessel  containing  sulphuric  acid. 
A  carafe  containing  water  was  attached  to  the  vessel  by  a  hose 
and  then  the  air  pump  was  started.  As  the  pressure  was  re- 
duced, the  water  in  the  carafe  would  boil,  due  to  its  own  heat, 
and  the  sulphuric  acid  would  absorb  the  water  vapor,  lower- 
ing the  pressure  still  further.  The  heat  of  vaporization  of 
the  vaporized  water  would  be  taken  from  the  water  in  the 
carafe  until  finally  this  removal  of  heat  would  cause  the  re- 
maining water  to  be  frozen. 

This  invention  has  been  followed  by  a  number  of  patents, 


38  ELEMENTS  OF  REFRIGERATION 

and  some  actual  installations.  John  Patten  has  invented 
apparatus  for  ice  manufacture  on  a  commercial  scale,  but  the 
value  of  such  installations  has  not  been  proven.  A.  J.  Stahl 
has  used  a  Patten  plant  at  South  Bend,  Indiana,  for  the  pro- 
duction of  30  tons  a  day.  The  drawback  is  to  obtain  the  high 
vacuum  necessary  for  freezing.  Water  boils  at  32°  F.  when 
the  pressure  is  less  than  0.08  lb.,  or  0.16  in.  of  mercury.  A 
still  lower  pressure  is  required  to  freeze  ice  in  a  short  time. 
That  such  ice  is  pure  is  assumed,  because  the  expansion  of 
the  gases  within  living  organisms  at  this  low  pressure  causes 
the  organism  to  rupture.  Under  very  low  pressures  the  evap- 
oration is  so  rapid  that  the  ice  forms  immediately. 

In  one  type  of  machine,  patented  by  J.  H.  J.  Haines  in 
1901,  an  air  pump  was  attached  to  a  vessel  containing  water 
to  be  frozen,  to  the  space  outside  this  vessel  and  within  an  iron 
receptacle,  and  to  a  vessel  containing  sulphuric  acid.  As  the 
air  pump  was  operated,  the  whole  system  was  exhausted.  The 
space  outside  the  water  vessel  being  exhausted,  prevented 
heat  from  passing  across  and  so,  when  the  pressure  was  low 
enough  for  the  water  to  boil  by  its  own  heat,  this  heat  could 
come  only  from  the  water,  since  the  vessel  was  well  insulated 
from  the  outside  by  the  vacuum  space.  This  abstraction  of 
heat  caused  the  remaining  water  to  freeze.  The  acid  in  the 
third  vessel  absorbed  the  water  vapor  formed  and  thus  reduced 
the  pressure. 

In  the  apparatus  patented  by  W.  T.  Hoofnagle  in  1903, 
water  to  be  made  into  ice  passes  through  a  vessel  A ,  Fig.  20, 
which  may  be  used  to  clear  the  water  or  filter  it.  It  enters 
the  chamber  B,  in  which  it  is  sprayed  over  a  series  of  trays; 
the  fan  at  the  bottom  keeps  up  a  circulation.  The  chamber 
is  connected  to  the  intermediate  cylinder  D  of  a  three-stage 
compressor  or  air  pump.  This  reduces  the  pressure  in  B  to 
such  an  extent  that  the  water  is  de-aerated,  and  a  small  amount 
of  evaporation  cools  the  water.  This  is  admitted  from  the 
pipe  E  into  a  chamber  F  by  two  valves.  The  chamber  F  is 
connected  to  the  low-pressure  cylinder  G  of  the  three-stage 
vacuum  pump  or  compressor.  The  air  and  water  vapor  drawn 


METHODS  OF  REFRIGERATION 


39 


out  by  G  is  sent  to  D  and  after  compression  it  is  finally  delivered 
by  H.  In  the  chamber  F  are  two  trays  which  are  oscillated 
by  rods  operated  by  cams.  When  in  the  position  shown, 
water  is  discharged  from  the  nozzles  on  these  trays,  and  as 
it  flows  along  the  tray  the  evaporation  of  water  under  the 
very  low  pressure  causes  the  remaining  water  to  freeze,  making 
a -cake  of  ice. 

It  is  considered  advisable  in  all  these  machines  to  spread 
the  water  in  a  thin  layer  so  that  freezing  may  take  place  readily, 


FIG.  20. — Hoofnagle  Vacuum  System  of  Ice  Making. 

as  evaporation  can  occur  over  a  large  surface.     Patten  sprays 
his  water  from  a  movable  head. 

Another  machine  for  which  claims  are  made  is  that  due  to 
Le  Blanc.  In  this  the  vacuum  is  obtained  by  steam  aspirators 
in  series,  each  compressing  the  air  exhausted  by  the  previous 
one.  By  using  the  Le  Blanc  condenser  pump,  this  apparatus 
is  used  to  advantage.  In  this  country  the  development  of  this 
machine  is  being  made  by  the  Westinghouse-Le  Blanc  interests. 
This  apparatus  is  being  developed  for  use  on  ships  of  the  French 
navy,  on  some  of  which  serious  accidents  occurred  by  the 


40  ELEMENTS  OF  REFRIGERATION 

bursting  of  the  parts  of  other  forms  of  refrigerating  apparatus. 
The  description  of  these  machines  is  found  in  Ice  and  Refrig- 
eration, for  July,  1912,  and  Aug.,  1910,  and  Power,  Jan.  n,  1916. 
The  chemical  process  refers  to  the  cooling  of  water  by  the 
addition  of  some  soluble  chemical.  If  ammonium  nitrate  is 
added  to  water,  the  temperature  of  the  solution  is  much  lower 
than  that  of  the  water,  a  tempera  ture^^rease  of  40°  being 
obtainable  in  this  way.  If  the  vessel  cJMaining  the  solution 
surrounds  some  object,  heat  will  be  abstracted  and  even  ice 
may  be  formed.  If  calcium  chloride  is  dissolved  in  water,  a 
reduction  of  30°  can  be  obtained  in  the  jemperature  of  the 
water.  After  this  the  salt  may  be  recovered  by  evaporation 
and  used  again.  This  principle  has  been  used  for  actual  appa- 
ratus to  produce  low  temperatures. 


CHAPTER  III 
THERMODYNAMICS  OF  REFRIGERATING  APPARATUS 


WHEN  ice 
perature  some  of 
be  possible  to  reduce 


is  difficult  to  tell  at  just  what  tern- 
forms,  and  also,  after  forming,  it  may 
perature  of  some  of  the  ice.     Hence 


11 


FIG.  21. — Cards  from  Air  Machine. 

the  amount  of  heat  required  to  form  a  pound  of  ice  is  not 
definite.  However,  if  ice  melts,  the  melting  does  not  begin 
until  32°  is  reached,  and  it  continues  at  this  temperature  until 
all  of  the  ice  is  melted.  For  these  reasons  the  amount  of 
heat  required  to  melt  a  pound  of  ice  is  used  as  a  unit  rather 
than  that  removed  to  make  a  pound  of  ice. 

Refrigeration  is  usually  measured  in  tons  of  ice-melting 
capacity  per  twenty-four  hours.  Since  the  latent  heat  of 
fusion  of  ice  is  143.4  B.t.u.  per  pound,  according  to  the  latest 

41 


42  ELEMENTS  OF  REFRIGERATION 

experiments,  this  unit   means   the  removal  of   286,800  B.t.u. 
per  twenty-four  hours,  or  199.2  B.t.u.  per  minute. 

The  air  refrigerating  machine  has  a  compressor  and  an 
expander,  the  indicator  cards  of  which  are  shown  in  Fig.  21. 
The  expansion  and  compression  curves  are  of  the  form  pvn  = 
const.,  and  the  compression  is  from  the  pressures  pi  to  p2. 
The  cards  are  shown  with  no  cleara^^  The  area  of  the 
card  is 

Area  3-2-10-11+ area  10-2-1-9  — area  4-1-9-11 
or 

/>2^2+  I     pdv^piVi  =  area,     „ •     .     .     .     (i) 

Jm 

XCVI     n,      const.  vl~n 
pdv  =  const.  I     v   ndv= — - — 
}„  i-» 

*= —  — •     •     • (3) 

i—  n 

Hence  Area  =  (^2  —  piVi)(  i -)     ....     (4) 

\       i  — n/ 

YI  \  f  \ 

n—i 


(6) 


n—i 
since  pv  =  MBT  for  perfect  gases, 

where   p  =  pressure  in  Ibs.  per  sq.ft.; 

v  =  volume  in  cu.f t. ; 
M  =  Ibs.  of  gas; 

B  =  constant  -      .Ig44 ; 

mol.  wt.  gas 

T  =  absolute  temperature  in  deg.  F. 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     43 

k  —  i 

By  the  thermodynamic  theory  B=——-Jcp. 

k 

Hence 

Area  =  work  =  — — MJcSTi  —  TI].   ...     (7) 

k     n-i 

The  temperature  T\  is  fixed  by  the  temperature  desired  in 
the  refrigerator.  If  the  system  is  open  (air  discharged  from 
expander  into  cold  room),  TI  is  the  temperature  of  the  room, 
while  if  a  closed  system  is  used,  T\  must  be  about  10°  below 
the  cold  room,  or  the  warmest  place  refrigerated,  since 


T    </>       n~~ T*    <f»  ( 9\ 

or 

rri  rr*     I  ft 

l2  =  J.l\  — 


The  work  of  the  expansion  cylinder  is 

6-T7].     .    .    ;.    (10) 


K     n—  i 

In  this  TQ  is  fixed  by  the  cooling  water  being  about  10°  F. 
above  the  water  on  the  opposite  side  of  the  cooler  metal  at 
the  point  where  the  air  leaves. 

In  most  compressors  and  expanders  the  action  is  so  rapia 
that  the  compression  is  adiabatic  and  n  equals  k.  This  gives 


r2-r1),  .....     (n) 
Workexp  =  MJcp(TQ-T7).  .....     (12) 

If  there  is  friction  of  100  /  per  cent,  the  net  work  required 
to  drive  the  machine  is 


Net  work=M/Cp(r2-r1)-(i-/)(r6-r7).    (13) 


44  ELEMENTS  OF  REFRIGERATION 

With  no  friction  the  work  is 

Net  work  =  MJcp[(T2-T1)-(T6-T7)],     1 


•     (14) 

ds) 


The  expander  cylinder  should  always  be  carefully  lagged 
to  prevent  the  entrance  of  heat,  but  in  the  compressor  the  use 
of  the  water  jacket  reduces  the  compression  line  by  abstracting 
heat  and  thus  saving  work,  j  If  it  is  assumed  that  the  exponent 


FIG.  22. — Card  with  Clearance. 

n  =  i.3$  in   the    compressor,  while  £  =  1.4,  the 

net  work  with  friction  becomes  u 

r> 

vf  %  M 

Net  work  iK 

i*fl 


expression  for 


(16) 


-r-),    .   (17) 


(18) 
(19) 


The  effect  of  clearance  is  seen  from  Fig.  22,  in  which  the 
compression  1—2  is  followed  by  the  discharge  2  —  2',  and  then 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     45 

the  air  2  '3,  which  is  retained  in  the  clearance  space,  expands 
from  2'  to  i'.  The  net  work  is  1-2-2'-!',  and  the  net  amount 
of  air  drawn  in  is  z'-i.  The  temperature  at  2'  is  that  at  2, 
hence  that  at  i'  is  the  same  as  at  i. 


k     n—  i  K     n—  i 

(T2-T1),      .  '.'..  V.    (20) 


n  — 


n—i 


(21) 


where  M  =  M\—  M'i,  or  the  weight  taken  in  from  i  to  i'. 

This  expression  is  the  same  as  that  in  Eq.  (7)  without 
clearance.  There  is  no  effect  of  clearance  on  the  work  of  a 
compressor  for  which  the  expansion  and  compression  lines  are 
complete,  and  have  the  same  exponent.  This  may  be  said 
of  an  expander  also,  when  the  cutoff  is  such  that  the  expansion 
is  complete  or  just  reaches  the  back  pressure  at  the  end  of  the 
stroke,  and  the  point  of  compression  is  such  that  the  compres- 
sion is  just  carried  to  the  initial  pressure. 

The  above  is  true  as  far  as  indicated  work  is  concerned, 
but  the  work  required  to  drive  the  compressor  is  slightly  greater 
with  clearance,  as  displacement  must  be  increased  for  a  given 
discharge  if  clearance  is  present,  and  there  is  consequently 
more  friction.  Let  the  clearance  2'  —  3  be  /  times  the  dis- 
placement Vi  —  V'z  or  D.  r 

That  is,  let 


The  volume  of  air  taken  in  is  V\  —  Vfi,  or 


46  ELEMENTS  OF  REFRIGERATION 

The  expression  within  the  bracket  is  known  as  the  clear- 
ance factor. 

V 


For  the  expander  with  complete  expansion  and  compression 

MBT7 


The  refrigeration  is  produced  by  adding  heat  to  the  air, 
increasing  the  temperature  from  T7  to  the  original  TI,  at 
constant  pressure.  Hence 

Refrigeration  =  M cp  ( T\  —  T7)  =  1 99 . 2  X  tons  of  ref . ;  .     .     .     (25) 
M  =  weight  of  air  required  per  minute; 
cp  =  specific  heat  at  constant  pressure  =  0.24  for  air. 

The  heat  removed  in  the  cooler  is  given  by 

t-qfln).      -.     .-   (26) 


M  =  weight  of  air  per  minute; 
G  =  weight  of  cooling  water  per  minute; 
<?'<mt  =  heat  of  liquid  of  cooling  water  at  outlet  temperature; 
q'm  =  heat  of  liquid  of  cooling  water  at  inlet  temperature. 

r™  •        •     -rt  *.     •>      Refrigeration  .    , 

The  expression,  in  B.t.u.  s,    ~—        -  is  known  as  the 

Work 

refrigerating  effect.    With  no  friction  this  becomes 

MC,(TI-TI)  i  (27) 

rp     rp  I 

Now 

rrr\  ) 

2  1  1 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    47 

since  t 

Ti     TI     \pj 

/.     Ref .  eff .  =  — =  = — ^-. 

T2  _       12  —  1 1 

This  shows  that  as  T2-Ti  becomes  smaller  the   refrigerating 
effect  or  the  refrigeration  per  unit  of  work  increases. 
The  general  expression  is 


Ref.eff.  = 


If  a  problem  is  given  the  following  steps  are  taken:  (a) 
TI  is  fixed  by  the  temperature  of  the  room  or  place  to  be  cooled 
and  TQ  by  the  temperature  of  the  cooling  water.  Of  course 
the  coldest  water  should  be  brought  in  contact  with  the  coldest 
air,  or  the  air  and  water  must  flow  in  opposite  directions  along 
the  cooling  surface,  giving  a  counter-current  flow,  (b)  By 
(18)  and  (19)  the  temperatures  T2  and  T^  are  found  after 

assuming  the  ratio  —  .     It  will  be  noted  that  T2  and  TV  depend 
pi 

upon  the  ratio  —  ,  and  not  upon  the  actual  values  of  the  pres- 
pi 

sures.  (c)  By  (25)  M,  the  weight  of  air  per  minute,  is  found 
for  a  given  number  of  tons  of  refrigeration,  (d)  G,  the  amount 
of  cooling  water  per  minute,  is  found  by  (26).  (e)  The  dis- 
placement of  the  compressor  per  minute  is  found  by  (23). 
(/)  The  displacement  of  the  expander  per  minute  is  given  by 
(24)  and  the  horse-power  is  given  by  dividing  (17)  by  33,000. 
H.P.  to  drive  machine  = 

^-ro-d-/)^-^)].      .    (29) 

33,  ooo          vi-// 

There  are  some  changes  to  be  noticed  before  proceeding 
with  a  problem.  If  in  the  expander  the  cutoff  is  too  late, 


48  ELEMENTS  OF  REFRIGERATION 

the  areas  7-10-9  and  11-12-13  will  be  lost,  decreasing  the 
work  done  by  the  expander  and  increasing  the  net  work  done 
by  motor  which  drives  the  machine.  Moreover,  TV  is  now 
higher  than  it  was  when  the  air  was  expanded  down  to  the 
lowest  pressure.  This  gives  less  refrigeration,  since  the  free 
expansion  7  to  9  is  throttling  action  and  will  not  cool  the  air. 
The  temperature  at  13  is  higher  than  the  temperature  TQ 
of  the  incoming  air,  because  T'i  is  higher  than  TI  would  have 
been  if  the  expansion  were  complete.  This  even  makes  TQ 


13  12 


FIG.  23.  —  Incomplete  Expansion  and  Compression  in  Expander. 

higher  than  it  should  have  been,  increasing  TV  and  still  further 
cutting  down  the  refrigeration 


This  incomplete  action  makes  the  displacement  Vg  —  Vi2 
less  than  it  would  be  with  complete  expansion  and  compres- 
sion, FIO  —  Fia.  This  is  the  only  advantage. 

Since  one  would  be  foolish  to  design  an  expander  with 
incomplete  expansion  and  compression,  this  will  not  be  further 
investigated  although  by  calculations  the  various  temperatures 
may  be  found  for  any  conditions. 

Note.  —  The  following  discussion  gives  the  temperatures,  assuming  no 
compression,  with  expansion  such  that  p^=2pl. 

Air  entering  at  temperature  T6  must  compress  the  clearance  air  ID, 
at  temperature  Tr,  from  pi  to  p2. 

The  energy  in  the  air  contained  in  the  cylinder  is  -£  —  . 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     49 

The  air  brought  in  from  the  storage  tank  to  bring  this  up  to  the  pres- 
sure p2  is  m  Ibs.,  and  the  energy  entering  from  the  tank  at  constant  pressure 

is  mcpT6.    The  energy  after  mixing  is  —-  —  . 

k—  i 


Hence 


. 

R—I         k  —  I 


(30) 


Now  the  weight  of  air  in  the  clearance  space  is 


-'-'£•  .........  oo 

The  temperature  of  the  mixture  in  the  clearance  space,  after  the  air 
enters  to  fill  the  space,  is  given  by* 


T  _  PJD 


(m+m')B     f  ID  (p2-pi)B       pi 

\(p2~Pl'~k^  ,       ID  J(k-i)cpr6+J\, 

L        JcpTe      +plBTr\ 

f*.  —  A.\          <h.    ~  A_7\.  J^A  /'fcT  _  T  A \32-/ 


When  the  remaining  air  (M—m)  passes  into  the  cylinder,  the  following 
equation  is  true: 


K  —  I 


—  I 

•       -       .       .       -       •       •       (33) 
r> 

In  this  TV  is  higher  than  T6  and  T6"  is  higher  than  T6.  If  now  the  air 
at  volume  Fo»  expands  from  pressure  p2  to  a  pressure  2/>i,  the  temperature 
of  discharge  will  be 

n-l 


50  ELEMENTS  OF  REFRIGERATION 

This  will  be  the  temperature  of  discharge,  since  the  free  epxansion 
is  a  throttling  action  of  constant  temperature.      Even  if  r6»  were  equal 

!  n-l 

to  r6,  Ti  would  be  higher  than  it  should  be  by  the  factor  2  »  .    This 
means  that  the  refrigeration  is  decreased. 

The  work  returned  by  the  expander  in  this  case  is 


(35) 


These  quantities  may  all  be  computed. 

The  compressors,  as  usually  constructed  and  used,  operate  in  such  a 
manner  that  complete  expansion  and  compression  result,  and  conse- 
quently there  is  no  effect,  due  to  clearance  space,  on  the  temperature 
or  work  of  that  part  of  the  apparatus. 

The  effect  of  moisture  in  the  air  is  to  reduce  the  refrigerating 
effect  and  increase  the  net  work.  Of  course,  this  moisture 
effect  is  not  felt  if  the  same  air  is  used4  over  and  over 
again,  since  the  first  chilling  dries  the  air  and  removes  the 
moisture. 

Air  contains  a  certain  amount  of  moisture.  The  amount 
is  told  by  a  hygrometer.  One  form  of  this  apparatus  consists 
of  two  thermometers,  one  of  which  has  a  wet  wicking  around 
it.  If  now,  these  two  thermometers  are  whirled  in  the  air, 
it  will  be  found,  usually,  that  the  wet-bulb  thermometer  Tvill 
read  less  than  the  dry  one.  The  amount  by  which  the  wet 
bulb  is  lowered  depends  on  the  moisture  present  in  the  air. 
If  the  air  is  saturated  with  moisture,  there  will  be  no  difference, 
while  if  the  air  is  dry,  there  is  a  large  difference  in  the  tem- 
peratures recorded  by  each.  The  amount  of  moisture  is  desig- 
nated by  relative  humidity.  Relative  humidity  is  the  ratio 
of  the  amount  of  moisture,  ma,  in  a  cubic  foot  of  air  compared 
with  the  amount  of  moisture,  ms,  to  saturate  it,  or 


/    ,N 

(36) 


p  =  relative  humidity  ; 
ma  =  amount  of  vapor  in  i  cu.ft; 
ms  =  amount  of  vapor  to  saturate  i  cu.ft, 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     51 

If  the  vapor  pressure  (vapor  tension  or  steam  pressure)  at 
a  given  temperature  is  ps,  the  actual  pressure,  pa,  exerted  by 
the  vapor  of  relative  humidity  p  is 


Now,  if  the  wet  bulb  reads  /«,  and  the  dry  bulb  td,  and  the 
barometer  reading  is  given  by  Bar,  then  according  to  Carrier 

_pw    Bar  -ft,  tg-ty 

~          ~ 


where       p  =  relative  humidity  ; 

pw  =  steam  pressure  corresponding  to  /«,; 
pd  =  steam  pressure  corresponding  to  /tf; 
Bar  =  barometer  reading; 
td  =  dry-bulb  reading; 
tto  =  wet-bulb  reading. 

If  the  air  of  relative  humidity  p  and  temperature  T\  enters 
the  compressor,  the  moisture  and  air  during  compression  will 
act  as  a  single  gas  and  the  temperature  T2  will  be  found  as 
before. 


or 


The  work  of  compression  will  be 

J[Mcp+mc'p][T2-Ti],     .....    V  (39) 


or 


ws  =  weight  of  i  cu.ft.  of  saturated  steam  at  temperature  T\\ 
ps  =  saturation  pressure  of  steam  at  temperature  T\  ; 
_iS44_ 


52  ELEMENTS  OF  REFRIGERATION 

When  this  air  is  cooled  to  temperature  T2)  an  investigation 
must  be  made  to  see  if  any  of  the  moisture  is  condensed.  If 
none  is  condensed  the  mixture  acts  as  a  gas  and 


If  now  VQmSQ>m  no  moisture  is  condensed  and 

m 


for  low  pressures,  and  then  m  —  ms§V§  =  amount 
condensed  in  the  cooler. 

In  the  first  case  m  Ibs.  enter  the  expander  and  in  the  second 
case  mSQVQ  enters  the  expander. 

This  moisture  is  condensed  and  frozen  as  soon  as  it  enters 
the  expander.  It  then  gives  up  the  heat 


5.4)  =c,     .....     (43) 
to  the  cylinder  walls  and  leaves  the  volume  of  the  air 

n-^p.    .  .  ',-.  '.".  .  (44) 

p2 

The  heat  c  taken  up  by  the  cylinder  walls  may  be  assumed 
to  be  gradually  restored  during  expansion.  If  this  is  divided 
between  the  temperatures  TQ  and  T7,  it  might  be  assumed 
that  the  amount  returned  from  the  walls  per  dt  degrees  is 


J-     — 


where  a  is  the  value  of  the  fraction. 

Hence  the  equation  for  work  at  the  expense  of  internal 
energy  and  the  heat  returned  is 

=  -pdV,     ..  ..,-'.    (45) 


THERMODYNAMICS  OF    REFRIGERATING  APPARATUS    53 


Jc       .  , 

(46) 


From  this  T7  may  be  found. 
The  work  done  is 


We*  =  p2  V&  +,pdv  -piV7 

=  MBTQ+J(mct+Mcv+ma)(TQ-T7)-MBT7 

=  J[mct+M(cv+AB)+ma][TG-T7] 

=  J[mc^Mcp+ma\[TQ-T7}  .......     (48) 

The  net  work  is 


r7][i-/].   .   (49) 

The  refrigeration  is 

JlfcJtTi-Tt]  .......     (50) 

The  refrigerating  effect  is 


Workn 


From  the  expression  for  refrigeration  it  is  noted  that  only 
air  is  considered  to  be  delivered  back  to  the  compressor,  and 
consequently  unless  this  air  received  moisture  from  the  space 
through  which  it  was  passed,  this  problem  is  of  little  value. 

If  a  large  quantity  of  water  is  injected  into  the  cylinder 
during  compression  to  reduce  the  amount  of  work  by  cooling, 
of  course  the  above  discussion  of  the  expander  would  be  im- 


54  ELEMENTS  OF  REFRIGERATION 

portant,  and  of  course  some  means  would  have  to  be  used  to 
remove  the  ice  formed  constantly  in  the  cylinder. 

If  the  water  injected  into  the  cylinder  at  each  stroke  is 
m  pounds,  the  following  equations  should  hold  for  the  com- 
pression stroke. 

J[Mc,dt+md(q'+xp)]  =  -PdV=-(P-p)dV-pdV,  .    (52) 
J[Mc,dt+mdq'+mpdx+mxdp]  =  -pdV-(P-p)dV, 


dq'  '  =  dt,  approximately; 
dV  =  m[(v"-v')dx+xd(v")]. 

=  Jm[p+Ap(v"-v')]dx+mpxdv" 

=  Jm(rdx+Apxdvfr).     .     .     .     .     .     .     .     (53) 

Now 

dp  =  dr-Apdv"-A(v"-v')dp, 

xdp=xdr-Apxdv"-Ax(v"-v')dp.    .     .    .     (54) 
But 


j.dt (55) 

Hence 


r    //  J  JvJWw  /     s\ 

v   =xdr-  — (56) 


ocrdt\\         M 

--r)  \  =  - 


MET 


xdr 


l  2  -  1 


[Mc,+m]  log.      +w       !  --f    =AMB  log,      .  .     (57') 

J-  1  " 

w 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS 

MBT 2 


V2 


Pa- pa 

',      • (60) 

(61) 


Ta,   V^_V^  _  V, 

"T2    ^T~AMBlCZeT2 


[Mc,+m}  log,  ^+^%-  -^±=AMB  ^ 


Equations  (59)  and  ($7")  will  give  ¥2  and  T2.  They  are 
to  be  solved  by  trial.  p2  and  r<z  are  fixed  by  Tz.  The  work 
done  in  the  compressor  is  given  by 


Wc  =  McP(T2  —  Ti)  +m(q2+X2r2  —  qi  —  Wi)  , 

=  McP(T2-Ti)+m(i2-ii)  ......     .     (62) 

The  remainder  of  the  problem  is  worked  out  in  the  same 
way  as  in  the  previous  case. 

To  apply  these  formulae,  it  is  desired  to  cool  a  room  to  o° 
with  cooling  water  at  60°  F.,  and  the  data  for  i  ton  of  refriger- 
ation is  to  be  found.  With  a  10°  rise  in  the  water,  a  10° 
difference  between  air  and  cooler  and  a  counter-current  air- 
cooler,  the  temperature  of  the  air  will  be  reduced  to  70°  F,, 
The  air  in  the  refrigerator  will  be  —  10°  F.  Hence 

Ti=-  10+459.6  =  449-6, 
T6=     70+459.6  =  529.6. 

Suppose  this  to  be  an  open  system  and  pi  is  14.7  Ibs.  per 
square  inch  absolute,  and  p2  is  44.1  Ibs.  per  square  inch  gauge. 


1.35-1 

--     1-35 


56  ELEMENTS  OF  REFRIGERATION 

The  refrigeration  per  pound  is  given  by 

=  22.6  B.t.u. 


The  weight  of  air  per  minute  per  ton=     ^'    =8.83  Ibs. 

22.6 

Cooling  per  minute  per  ton  =  8.83  X  .24(645  —  530)  =  244.  B.t.u. 

Amount  of  water  per  minute  per  ton  =  -^  =  24.4  Ibs. 

10 

The  work  with  15%  friction  is  given  by 
Net  work  per  minute  per  ton 

=8.83X0.2411.  10X1.15(645  -450)  -0.85  x  (530-356)] 

=  209.5  B.t.u. 

Horse-power  per  ton  of  refrigeration  =  —  —  =4.95. 

42.42 

Clearance  factor  in  compressor  with  2%  clearance 

i 

=  I  +0.02  —  0.02  X  (4)  L35  =  0.964. 


Clearance  factor  in  expander  with  2%  clearance 


i 


=  i  +0.02  —  0.02  X  (4)1-4  =  0.966. 
Displacement  per  minute  per  ton  for  compressor 


I4.7Xl44XO.964 

Displacement  per  minute  per  ton  for  expander 


=  u- 


I4.7Xl44XO.966 

Refrigerating  effect 

450-356 


i. loX  115  X  (645 -450) -0,85(530-356)     99 


=      =  0.95. 


THERMODYNAMICS  OF  KEFRlGERATINa  APPARATUS    57 


Am  MACHINE 

In  the  dense  air  machine,  or  closed  system,  the  initial  gauge 
pressure  is  taken  as  44.1  Ibs.  per  square  inch  and  the  pressure 

p2  is  220.5  Ibs.  per  square  inch  gauge.     The  ratio  —  is  then 

Pi 

23^.2  - 

'    or  4.     Hence,  if  computations  are  made  as  above  there 


will  be  no  change  in  any  results  until  the  displacement  is  reached, 
when  it  will  be  found  that  these  quantities  are  reduced  to 
j  of  their  previous  values,  giving 

Displacement  per  min.  per  ton  for  compressor  =  26.0  cu.ft. 
Displacement  per  min.  per  ton  for  expander     =  20.5  cu.ft. 

The  low  performance  of  the  air  machine  coupled  with  the 
large  size  of  the  cylinders  of  open  systems  has  caused  this  machine 
to  give  way  to  the  vapor  machines.  Since  air,  however,  costs 
nothing  and  will  not  spoil  substances  nor  poison  persons  if 
the  system  leaks,  and  since  machines  built  for  air  are  reliable, 
these  machines  are  found  in  use  to  a  certain  extent,  especially 
on  vessels. 

The  thermodynamics  of  vapor  machines  is  best  studied 
from  a  temperature-entropy  diagram.  This  diagram  is  formed 
by  plotting  the  entropy  of  the  liquid  s'  against  absolute  tem- 
perature, getting  the  curve  AB  which  cuts  the  zero  entropy  at 
32°  F.,  since  that  is  the  point  from  which  entropy  is  measured. 
The  value  of  s'  has  been  found  by  plotting  the  specific  heat 
of  liquid  c  against  loge  T  and  finding  the  area  to  any  point. 


4Q2 


For  temperatures  below  32°  F.  the  value  of  s'  is  a  negative 
quantity  as  is  the  heat  of  the  liquid  q'  which  is  given  by 


r'=  Ccdt. 

J* 


(64) 


58  ELEMENTS  OF  REFRIGERATION 

From  this  curve  AB,  known  as  the  liquid  line,  the  entropy 
of  vaporization,  —  is  laid  off,  giving  the  line  CD,  the  saturation 

line. 

If  the  distance  EF  is  now  divided  into  proportional  parts, 
and  this  is  done  with  lines  at  other  temperatures  and  corre- 
sponding points  are  united,  the  light  dotted  lines  shown  in  the 
figure  are  obtained.  These  are  lines  of  constant  quality.  On 
these  the  quality  or  the  amount  of  vapor  in  one  pound  of  vapor 
and  liquid  is  constant.  For  that  reason  these  are  also  called 
lines  of  constant  vapor  weight.  It  is  known  that  the  entropy 
of  vaporization  for  a  quality  x  is 

xr 
T 

"PC* 

For  this  reason  the  ratio  — - ;  =  x. 


From  the  quality  x  the  volume  of  i  Ib.  of  mixture,  v,  may 
be  found  since 

(65) 


v  =  vol.  of  i  Ib.  of  mixture; 
z/'  =  vol.  of  i  Ib.  of  saturated  vapor; 
0'  =  vol.  of  i  Ib.  of  liquid. 

Now  (i—  x)  is  the  amount  of  liquid  present  in  i  Ib.,  since 
x  is  the  weight  of  the  vapor.  The  volume  of  i  Ib.  of  liquid  is  v' 
cu.it.,  and  the  volume  of  i  Ib.  of  dry  vapor  is  v"  cu.it.  In 
general  the  quantity  (i—x)v'  is  so  small  that  it  may  be 
neglected,  giving 

v=xv"  .........     (66) 

The  quantities  v'  and  v"  are  found  in  the  tables  of  the 
properties  of  vapors,  and  for  any  quality  x  at  a  given  tem- 
perature, the  volume  may  be  found.  Conversely,  if  the  volume 
be  known,  the  quality  at  any  pressure  may  be  found  by 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    59 

and  from  this  equation  the  values  of  x  for  the  same  volume 
at  different  temperatures  may  be  computed,  and  on  joining 
these  points,  lines  of  constant  volume,  shown  dotted  in  the 
figure,  may  be  drawn. 

One  other  thermodynamic  quantity  which  is  of  great  value 


FIG.  24. — r.S1.  Diagram  for  Ammonia  with  Thermal  Lines. 

may  be  found  from  the  quality  x.     This  is  the  heat  content  2, 

which  is  defined  by 

i  =  A(u+pv) (67) 

«  =  intrinsic  energy  of  i  Ib.  of  substance; 
p  =  pressure  in  pounds  per  square  foot; 
v  =  volume  of  i  Ib.  in  cubic  feet; 


60  ELEMENTS  OF  REFRIGERATION 

For  a  mixture  of  a  liquid  and  a  vapor 

Au  =  q'+xP  .......     .     (68) 

u  =  intrinsic  energy  of  i  Ib.  of  substance  in  foot-pounds; 
A-  •   T   • 


<?'  =  heat  of  the  liquid  of  i  Ib.  in  B.t.u.; 
p  =  internal  heat  of  vaporization  of  i  Ib.  in  B.t.u. 

Hence 


=  q'+xp+xAp(v"-v')+Apv'. 

By  definition  the  heat  of  vaporization,  r,  is  equal  to  the 
internal  heat  of  evaporation  p  plus  the  external  work  when 
i  Ib.  of  h'quid  is  changed  into  vapor. 

r  =  p+Ap(v"-vr). 
From  this 

i  =  q+xr  -\-Apv'  .......     (69) 

Since  Apv'  is  a  very  small  quantity,  it  is  customary  to 
consider  the  approximation 

i  =  q+xr,      .......     (70) 

as  true. 

Since  in  most  problems  the  value  of  one  i  is  subtracted 
from  another,  the  small  term  which  is  almost  the  same  in  each 
heat  content  would  be  canceled  out,  and  for  that  reason,  al- 
though an  approximation,  the  use  of  Eq.  (70)  would  lead  to 
no  large  errors  as  it  is  ordinarily  employed. 
Since 

i  =  q'+xr, 


and  for  any  given  value  of  *  at  any  given  temperature  the 
quality  x  may  be  found  and  by  connecting  the  points  of  the 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     61 


same  i  at  different  temperatures,  lines  of  constant  heat  content 
may  be  found.     These  are  shown  by  dotted  lines. 
The  above  equations  may  be  written  for  mixtures: 


0.25  0.50  0.75  1.00  1.35  1.50 

Entropy 

FIG.  25.— Heat  Content-Entropy  (7.5.)  Diagram. 
/  ,  XT 


v=xv 


For  M  pounds  of  substance 

+          or 


(66) 
(70) 


-Ji),      •    -     (7O 


62 


ELEMENTS   OF  REFRIGERATION 

=  Mx<v"  or    &V  =  M(v2-vi),      .     .     (66') 

=  M(q'+xr)      or      ±I  =  M(i2-ii).       .     .     (70') 


1.60 


0.50 


0.10  0  0.10  0.20  0.30 

Entropy 

FIG.  26. — I.S.  Diagram  with  Inclined  Co-ordinates. 


0.40 


It  should  be  remembered  that  in  this  saturated  region  the 
pressure  is  fixed  for  any  temperature,  by  the  characteristic 
equation  of  the  vapor,  and  when  the  words  "  any  temperature  " 
were  used  above,  the  words  "  any  pressure  "  could  have  been 
used. 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     63 

Since  i  is  an  important  quantity  in  most  problems  relating 
to  refrigeration,  and  since  entropy  is  needed  in  discussing 
adiabatics,  the  coordinates  i  and  s  are  often  used  for  a  diagram, 
shown  in  Fig.  25.  This  is  sometimes  called  a  Mollier  diagram. 
In  it  the  line  of  any  temperature  or  pressure  is  found  by  com- 
puting the  i  and  s  for  a  given  x.  If  the  points  of  the  same 
quality  are  united,  lines  of  constant  quality  may  be  found,  while 
points  of  the  same  pressure  give  lines  of  constant  pressure. 

This  diagram  as  drawn  with  the  axes  of  coordinates  at  right 
angles  is  such  that  for  a  given  range  of  temperatures,  there 
is  much  of  the  figure  which  is  of  no  value.  To  correct  this 
the  angle  between  the  axes  is  made  much  smaller  than  90° 
by  some  authors  and  constructors  of  charts,  giving  Fig.  26 
for  the  Mollier  chart. 

If  a  mixture  is  heated  until  all  of  the  liquid  is  evaporated, 
the  further  addition  of  heat  at  constant  pressure  will  increase 
the  temperature  of  the  substance  above  its  saturation  tem- 
perature, or  it  will  superheat  it.  The  difference  between  the 
temperature  of  the  substance  and  its  saturation  temperature 
is  known  as  the  degrees  of  superheat. 

Deg.  superheat  =  r8up  —  T^t. 

TBUQ  =  absolute  temperature  of  the  superheated  substance; 
Ts&t  =  absolute  temperature  of  saturation  corresponding  to 

the  pressure; 

4uP  =  rsup  —  459.6  =  Fahrenheit  temperature  of  the  substance; 
/sat  =  Ts&t-  459-6. 

If  the  entropy  and  heat  content  are  increased,  their  values 
will  be  given  by 


~  ......  (70 

T 

rsuv  rTmv> 

I       cpdt+Apv'  =  q'+r+  j       cpdt.    .     (70") 

jTaAt  JTsat 


64 


ELEMENTS  OF  REFRIGERATION 


The  specific  heat  of  superheated  vapor  is  given  by  the 
letter  cp.  This  may  be  a  constant  or  a  variable.  In  most 
vapors  used  for  refrigeration,  the  value  of  cv  is  considered 
constant  for  lack  of  better  information.  The  value  of  v  is 
found  from  the  characteristic  equation  of  the  superheated  vapor, 
which  is  usually  taken  in  the  form 


p(v-c)=BT+apa. 


(72) 


FIG.  27. — Cards  from  Vapor  Machines. 

Using  these  equations,  Figs.  24,  25,  and  26  are  carried  out 
beyond  the  saturation  line  into  the  superheated  region  as 
shown. 

The  p-v  diagram  from  the  vapor  machines  with  an  expander 
is  shown  in  Fig.  27,  considering  no  clearance,  as  compression 
and  expansion  are  complete.  The  vapor  is  drawn  into  the 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    65 


/ 

/ 

'  ;  \ 

2' 

5 

/ 

75°  F                                    \ 

1^^^^ 

i90°  32°F 

§ 

A 

\ 

i 

\ 

4 

/ 

- 

\ 

10°  F 

\ 

1' 

J 

i 

6 

0" 

6' 

1 

\ 

/ 

\ 

/ 

\ 

/ 

\ 

] 

• 

• 

- 

•• 
• 

\ 

-•. 

Abs.  Zero 

a 

6 

c 

d 

•' 
c 

/ 

9 

0. 

20 

0 

0.25 

0.50               0.75                1.00 

1.25 

Entropy 

FIG.  28. — T.S.  Diagram  of  Cycle  of  Refrigerating  Machine  Using  a  Volatile 

Fluid. 


66 


ELEMENTS  OF  REFRIGERATION 


compressor  from  4  to  i  and  is  compressed  from  i  to  2.  This 
compression  not  only  raises  the  pressure,  but  also  the  tem- 
perature at  which  the  liquid  will  boil  or  the  vapor  will  con- 
dense. Hence,  if  sufficiently  high,  the  pressure  will  have  a  sat- 
uration temperature  above  the  temperature  of  a  water  supply, 
and  if  passed  through  condenser  tubes  with  water  on  the  out- 


Entropy 


FIG.  29. — I.S.  Diagram  of  Cycle  of  Refrigerating  Machine  Using  a  Volatile  Fluid. 

side,  the  vapor  will  condense.  The  vapor  is  driven  out  from 
2  to  3  into  the  condenser  in  which  heat  is  removed  to  condense 
the  vapor.  The  liquid,  which  occupies  a  very  small  volume 
3-5,  is  admitted  to  the  expander  and  expands  from  5  to  6, 
after  which  it  is  allowed  to  enter  the  expansion  coils,  where  it 
abstracts  heat  from  the  cool  material  outside  of  the  coils  because 
its  pressure  has  been  so  reduced  that  the  temperature  of  boiling 
is  lower  than  the  low  temperature  of  the  substance  around 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     67 

the  coils.     The  liquid  boils  and  finally  occupies  the  volume 
4-1.     The  combination  of  these  two  cards  gives  the  net  card 


Constant  Heat  Content 


FIG.  30. — I.S.  Diagram  of  Cycle  of  Refrigerating  Machine  (Inclined  Axes). 

1-2-5-6,  in  which  1-2  and  5-6  are  adiabatic,  and  2-5  and  6-1 
are  constant-pressure  lines. 

This  figure  may  be  placed  on  the  temperature-entropy 
diagram,  Fig.  28,  or  on  the  i-s  diagram,  Figs.  29  and  30. 

On  the  line  1-2  the  compression  carries  the  vapor  into  a 


68  ELEMENTS  OF  REFRIGERATION 

drier  region,  as  drawn  X2  =  i,  so  that  the  vapor  is  always  sat- 
urated and  some  liquid  is  present.  This  is  known  as  wet 
compression.  If,  however,  x\  as  at  i'  were  unity,  the  com- 
pression i  '-2'  would  carry  the  vapor  into  the  superheated 
region.  This  is  known  as  dry  compression.  The  compression 
from  i  to  2  would  require  work  shown  by  the  area  1-2-3-4 
on  Fig.  27. 

A  X  work  per  pound  =  q2+X2p2  —  gi  —  xiPi  +Ap2V2— 


i2  —  ii.        .     .     (73) 

In  the  superheated  region  the  work  per  pound  would  still  be 
given  by 


(73') 
In  the  same  manner  the  expression  for  work  in  the  expander 

AW.=M(is-io)  .......     (74) 

Now  the  work  required  in  the  expander  is  so  slight  that 
this  part  of  the  apparatus  is  omitted,  the  complication  and 
friction  being  of  greater  value  than  the  work  regained.  In 
that  case  the  net  work  per  minute  becomes 

.    .    .    .     (73") 


This  expression  for  work  is  shown  by  the  area  1-2-5-4 
on  Fig.  28,  since, 


Area  (b-h-$-2)  =  qf 
Area  (a-^-i-f)  —  area  (a-^-h-b)  =#in+<?'i  =i\» 

'l  is  a  negative  quantity.) 

Area  (b-h-$-2)  -*•  area  (0-4-  1-/)  +area  (a-^-h-b}  =  i%  —  ii 
=  Area  (1-2-5-4). 


THERMODYNAMICS   OF  REFRIGERATING  APPARATUS     69 

On  Figs.  29  and  30  there  is  no  area  equal  to  this  work, 
but  the  difference  between  the  coordinate  values  of  i  at  2  and 
at  i  will  give  (jiz—ii)  or  the  work. 

In  these  figures  the  lines  1-2  represent  wet  compression, 
while  i  '-2'  represent  dry  compression. 

The  pressure  is  actually  reduced  from  p2  to  pi  through  a 
throttle  valve.  Throttling  action  is  of  constant  heat  content. 
Hence  the  line  5-6  must  be  changed  to  5-6',  or  from  a  reversi- 
ble adiabatic  or  constant  entropy  line  to  a  non-reversible 
adiabatic  or  constant  heat-content  line.  This  makes 


The  heat  removed  from  the  refrigerator  is  that  to  pass 
from  6'  to  i,  and  hence  this  heat  is 


Ref.  =M(ii—  zV)  =  i99.2Xtons         ....     (75) 
=  M(ii  -  is)  =MX  area  (e-6'-i-f)  . 

By  this  equation  the  quantity  M  per  minute  is  found. 

The  heat  removed  from  the  ammonia  in  the  condenser  is 
given  by  the  heat  under  the  line  2-5  or  2  '-5.  This  is  the 
area  (c-$-2-f).  In  any  case  this  is  given  by 

q'i)J      .     .     .     (76) 


G  =  lbs.  of  cooling  water  per  minute; 
g'0  =  heat  of  the  liquid  of  cooling  water  at  outlet; 
(fi  =  heat  of  the  liquid  of  cooling  water  at  inlet. 

These  formulae  hold  for  wet  or  dry  compression.  The 
points  i  and  2  are  on  the  same  adiabatic,  and  hence  the  values 
of  i\  and  i%  are  found  in  the  same  entropy  column. 

At  times  after  the  ammonia  is  condensed  the  liquid  is 
passed  through  pipes  surrounded  by  cold  water  and  the  liquid 
is  cooled  down  the  liquid  line  to  5'.  This  is  known  as  after  cool- 
ing. This  increases  the  amount  of  cooling,  and  if  the  water  is 
available  this  gain  will  increase  the  refrigeration,  as  %  is  equal 


70  ELEMENTS  OF  REFRIGERATION 

to  ig  or  iy,  whichever  represents  the  condition  of  the  liquid 
entering  the  throttle  valve.  It  will  be  seen  that  throttling 
action  has  changed  i$  to  i&,  thus  losing  the  refrigeration 


The  quantities  may  all  be  found  on  the  I-S  diagrams  as 
coordinates  of  the  points.  The  lines  are  of  peculiar  shape. 
Adiabatics  are  lines  of  constant  entropy  and  throttling  lines 
are  lines  of  constant  heat  content.  Constant  pressure  lines 
are  straight  lines  in  the  saturated  region,  but  curve  when  the 
superheated  region  is  reached. 

The  loss  of  refrigeration  due  to  the  elimination  of  the  expander 
referred  to  above,  and  that  of  the  work  of  the  expander  are 
considered  to  be  offset  by  the  simplicity  of  the  apparatus. 

The  refrigerating  effect  is  given  by 

Ref.effect=  -^      .....     (77) 


The  displacement  per  minute  of  the  compressor  is  given  by 

(78) 


n  =  i.2  for  wet  compression  or  1.33  for  dry 

The  clearance  factor  given  in  the  denominator  of  this 
expression  is  the  same  as  that  in  any  compressor  for  the  lines 
1-2  and  i/-2/  are  similar  lines  of  the  form  pvn  =  const.  There 
is  no  reason  why  the  quality  at  2  and  that  at  2'  should  be 
different,  and  if  they  are  the  same  the  lines  are  the  same. 

The  volumetric  efficiency  of  a  compressor  is  the  ratio  of 
the  free  substance  actually  pumped  to  the  displacement. 


Vol. 


D         L  \pi/  J  100 


Voorhees  has  patented  a  scheme  by  which  certain  savings 
may  be  effected  when  there  is  a  chance  to  use  two  different 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    71 

temperatures  of  cooling.  In  most  cases  there  are  certain  sub- 
stances or  spaces  to  be  cooled  to  temperatures  not  as  low  as 
those  of  other  parts  of  the  system,  and  for  such  he  proposes 
to  expand  part  of  the  ammonia  to  one  pressure,  and  another 


FIG.  31.— Effect  of  Clearance. 

part  to  a  lower  pressure.  If,  now,  the  compressor  is  large 
enough  to  displace  the  proper  amount  of  vapor  at  the  lower 
pressure  and  at  the  end  of  the  suction  stroke  a  valve  is  opened 
to  a  place  of  higher  pressure,  the  spring  suction  valve  to  the 


FIG.  32.— Multiple  Effect  Indicator  Cards. 

low-pressure  place  is  closed  and  vapor  rushes  in  from  the  place 
of  higher  pressure  and  fills  the  cylinder  to  that  pressure  before 
the  return  stroke  is  started.  Voorhees  calls  this  a  multiple 
effect.  The  indicator  card  is  shown  in  Fig.  32.  The  advantage 
of  this  apparatus  is  that  for  the  part  of  the  heat  abstracted 


72  ELEMENTS  OF  REFRIGERATION 

at  higher  temperature,  less  work  has  to  be  done.  1-2  would 
be  the  line  for  the  low-pressure  compression.  i'-2f  is  the 
combined  line.  The  work  done  is  4-1-1  '-2'-$.  The  saving 
has  been  i'-6-i.  Voorhees  accomplishes  this  by  allowing  the 
piston  of  the  compressor  to  override  a  port  at  the  end  of  the 
stroke,  the  port  leading  to  the  space  carrying  the  high-pressure 
vapor. 

All  of  the  data  for  any  compression  machine  using  a  volatile 
liquid  and  its  vapor  .can  now  be  applied.  Several  problems 
will  be  worked  out. 

PROBLEM 

As  a  problem  in  the  above  theory,  suppose  it  is  desired 
to  keep  a  room  at  o°  F.  with  water  at  60°  F.,  and  the  amount 
of  refrigeration  is  to  be  i  ton.  Investigate  for  wet  and  dry 
compression  with  ammonia  and  for  wet  compression  with  CO 2 
and  S02. 

The  temperature  of  the  vapor  in  the  condenser  for  a  10° 
rise  and  a  10°  difference  will  be  80°  F.  The  temperature  of 
boiling  with  a  5°  rise  in  brine  temperature  and  a  10°  difference 
in  temperature  between  brine  and  room  and  brine  and  vapor 
will  be  -25°. 

AMMONIA — WET 

p2    corresponding  to  80° 153 . 9 

xz.. i.o 

s2 1.0354 

*2 557-° 

*a 53-6 

iy   (if  after  cooled  to  70°) 42 .  i 

pi     corresponding  to  —25° 15 .61 

i.o3.c-4-(-.oi29o)  o  « 

Xi  = 0.055 

1-3599 

5i 1-0354 

^=2'+^= -59.8+0.858X591. 1=447-2  . 

21=0.858X16.95 14-5 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     73 

Refrigeration  per  Ib.  of  NHs  —  i\  —  iy  =447.2  —  42.1  =405.1. 

Weight  of  NHa  per  min.  per  ton  of  ref.  =—    -  =0.49. 

405.1 

Cooling  per  Ib.  of  NHs  =22  —  23'  =  557.0  —  42.1  =  514.9. 


Lbs.  water  per  Ib.  NH3  =  ^  -v  =  5i.5  Ibs. 

10 

H.P.  per  Ib.  NH3  per  min.  =  — ^—^  =   557~447   =  2.9. 

42.42  Xeff.     42.42X0.90 

Volume  per  Ib.  of  NH3  =  14.5  cu.ft. 

Cooling  water  per  min.  per  ton  =  5 1.5X0.490  =  2 5. 2  Ibs.  per 

min. 

H.P.  per  ton  of  capacity  =  2. 9X0.490  =  1.42. 
Displacement  of  piston  per  min.  per  ton  with  no  clearance 

=  14.5X49  =  7. i  cu-ft- 

/iq2  o\_L 

Clearance  factor  with  2%  clearance  =  i  +0.02  —  0.02 1  -?^~  1 1.3 

\  15.0  / 

=  1.02  —  0.135=0.885. 

Displacement  per  min.  per  ton  =  -^-  =8.0  cu.ft.  per  min- 

per  ton. 
Refrigerating  effect  with  friction  =  4C 


no 

AMMONIA — DRY 

pi  (-25°  F.) 15.6 

#1 i.o 

si i. 2310 

»i l6-95 

p2  (80°  F.) .1^.0 

*  **     \  /  \}*J      " 

52 I.23IO 

quality 201°  sup. 

it.  . 680.  i 

*3 53-6 

iy 42'T 


74  ELEMENTS  OF  REFRIGERATION 

Refrigeration  per  Ib.  of  NH3=^i  —  iy  =  531.3  —  42.1  =489.2. 

Weight  of  NHs  per  min.  per  ton  of  ref.  =  =0.407. 

489.2 


Cooling  per  Ib.  of  NHs  =  f2  —  iy  =  680.  1—42.1  =638.0  B.t.u. 


Lbs.  water  per  Ib.  NH3=        =  63.8  Ibs. 

10 

TT  -n          ii_   XTTT  -  iz  —  ii         680.  i  —  511.3 

H.P.  per  Ib.  NH3  per  mm.  =  —  ?  —  -  —  =  -  ^—  ^  =  3.90. 

42.42  X.  90      42.42  X.  90 

Volume  per  Ib.  of  NHs  =  16.95. 

Cooling  water  per  min.  per  ton  =  0.407X63.8  =  2  5.9  Ibs. 
H.P.  per  ton  capacity  =  0.407X3.  90  =  1.5  85  H.P. 
Displacement  per  min.  per  ton,  no  clearance 

=  0.407X16.95  =  6.9  cu.ft. 

Clearance  factor  with  2%  clearance 


=  I  +0.02-0.02  (  ^M  )  1.33  =0. 

\  iq.6/ 


=  0.91 


Displacement  per  minute  per  ton=— —  =7.59  cu.ft. 

0.91 

Refrigerating  effect  =  4  ^'2  Q'9  =  2.96. 


CO2— WET 

pi  (at  -25°  F.) 201.3  Ibs. 

p2  (80°  F.) 967  Ibs. 

X2 I  .  O 

S2 O.I 508 

2*2-  •  •  •  , 81.52 

Si o. 1508 

o.i  1508+0.0560 

xi= — —       — — 0.706 

0.2927 

ii  =  —26.99+0.706X127.28..  63.0 

vi  =0.451  X.  706 0.318 

i= 26.21 


THERMODYDAMICS  OF  REFRIGERATING  APPARATUS     75 

Refrigeration  per  Ib.  of  CO2=*i  —  23'  =  63.0  —  26.2=36.8. 

Weight  of  CO2  per  min.  per  ton  of  ref.  =  I^'<?  =  $.42. 

30.8 


Cooling  per  Ib.  C02  =  *2  —  *V  =  8i.  52  —  26.21  =  55.31. 
Lbs.  of  water  per  Ib.  of  CO2  =  ^^  =  5.53. 


81.52  —  63.0         18.^2 

H.P.  perlb.  CO2permm.=  —  *  -  ^r~  =  -  -  =  0.547. 

42.42X0.80     42.42  X.8o 

(80%  eff  .  due  to  high  pressure.) 
Cooling  water  per  minute  per  ton  =  5.42  X  5.  53  =30.0. 
H.P.  per  ton  capacity  =  0.547X5.  42  =  2.  96. 
Displacement  per  min.  per  ton,  no  clearance 

=  5.42X0.318  =  1.72  cu.ft. 
Clearance  factor  i%  clearance 

=  1+0.01—0.01X1^—^  11^  =  0.076. 

\20I/ 
I  72  • 

Displacement  per  minute  =—-^-  =  1.76  cu.ft. 

O.Qo 

Refrigerating  effect  =  ^^  =  2.  48. 
10.52 

This  )ow  effect  is  due  to  the  peculiar  properties  of  CO  2 
at  the  temperature  used.  At  other  pressures  the  properties 
are  such  that  CCb  gives  a  much  higher  refrigerating  effect  than 
other  substances.  The  temperature  of  85°  F.  is  not  far  from 
the  critical  temperature  of  CO  2  and  for  this  reason  the  results 
are  as  above.  On  the  T-S  diagram  of  Fig.  33  this  is  shown 
clearly  by  1-2-5-6'.  Plank  in  the  Zeitschrift  fur  der  Gesamte 
Kitlte  Industrie  proposes  that  if  the  critical  temperature  is 
passed,  the  cooling  of  the  superheated  vapor  in  the  condenser 
should  be  followed  by  a  further  compression,  after  which 
a  second  cooling  is  resorted  to,  and  that  this  reduces  the 
entropy  so  that  the  state  after  throttling  is  changed  to  give 
greater  refrigeration.  The  results  are  shown  in  the  table 
on  the  following  page. 


' 


76 


ELEMENTS  OF  REFRIGERATION 


Condenser  Pressure, 
Atmospheres. 

Temperature  of 
CO2  at  Exit  from 
Condenser. 
Deg.  F. 

Gain  in 
Refrigeration. 
Per  cent. 

Gain  in 
Performance. 
Per  cent. 

80 
90 

91 
IOI 

48 
46 

28 
32 

IOO 

III 

44 

35 

Fig.  33  shows  the  compression  beyond  the  critical  pressure. 
The  use  of  the  figure  is  similar,  however,  to  that  of  the  regular 


En  tropy 

FIG.  33.  —  CO2  Diagram  on  T.S.  Co-ordinates  Showing  Plank's  Duplex 
Compression. 

T-S  diagram.  i-2II-5n-5III-5IV-6111  is  the  Plank  cycle.  The 
refrigeration  under  6///-6/  is  gained  by  the  compression  5  "-5"' 
and  the  cooling  5"'-5Iv.  The  cycle  iy-2,-5,-6,  is  one  near 
the  critical  temperature  in  which  the  refrigeration  under  6y-iy 
is  small  when  compared  with  the  work  7-1^2^5^7. 

SO2  WET 
p2  for  temperature  80°  ............   59  .  7 


s2  ......  ......................  ••••  0.3020 

i2  ..............................  162  .  08 

i     .............................    .       12.62 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    77 

pi  for  -  25°  .....................     4.98 

Si  ..............................     0.3020 

gi..  3020+0.0370.  _  o 

0.4062 
*i=-  17.15  +176.5X0.835  ........  130.1 

^1  =  14.13X0.835  .................   ii.  8 


Refrigeration  per  Ib.  of  S02  =  (z'i  —  iy)  =  130.1  —  12.62  =  117.5. 
Weight  of  862  per  min.  per  ton  of  ref.  =—    L  =  1.695. 
Cooling  per  Ib.  of  802=^2  —  iy  —  162.  08—  12.62  =  149.46. 

Lbs.  of  water  per  Ib.  802=—  -^^—  =  14.95. 

10 

ir      r  o/^  •        162.08  —  130.1 

H.P.  per  Ib.  of  862  per  mm.  =  —  —=0.84. 

42.42  X.  9 

Cooling  water  per  min.  per  ton  =  1.69X14.95  =  2  5.  3. 
H.P.  per  ton  of  ref.  =0.84X1.69  =  1.42. 
Clearance  factor,  2%  clearance 

=  1+0.02-0.02(^^)1^26  =  0.88. 
\4.98/ 

Displacement  per  ton  of  refrigeration,  no  clearance 

=  1  1  .80  X  i  .69  =  20.00. 

Displacement  per  ton  of  ref  rigeration  =  —  -  =  22.7. 

o.oo 

Refrigerating  effect  =  —        0  '9  =  3.3i. 
31.98 

With  the  ammonia  system  it  was  seen  that  1.42  H.P.  is 
required  to  produce  a  ton  of  refrigeration.  If  this  engine  is 
assumed  to  use  30  Ibs.  of  steam  per  H.P.  hour  and  if  auxili- 
aries require  20%  of  the  steam  of  the  main  engine,  while  the 
boiler  evaporates  9  Ibs.  of  steam  per  pound  of  coal,  the  coal 
required  would  be 

1.42x30x24x1.20    61bSj 

9 


78 


ELEMENTS  OF  REFRIGERATION 


492°  32  F 


Abs.  Zero 


-20        <70         65  .Eatropy  6   6' 

FIG.  34. — Effect  of  Temperature  Range  on  Refrigerating  Effect. 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     79 

For  ice  making  it  takes  if  to  2  times  the  tons  of  ice  in  re- 
frigeration units,  or  272  Ibs.  of  coal  would  be  required  per  ton 
of  ice.  This  gives  practically  yj  tons  of  ice  per  ton  of  coal. 
This  is  quite  a  common  figure  and  one  to  keep  in  mind.  Of 
course,  as  can  be  seen  from  the  diagrams,  the  temperature 
range,  or  particularly  the  temperature  of  the  cooling  water, 
plays  an  important  part  in  the  economy  of  a  station.  Thus  in 

Fig.  34  if  1 234  represent  a  cycle,  the  performance  is  — 

1-2-3-8 

If,  now,  the  temperature  of  the  cooling  water  can  be  lowered 
to  2 '-3',  the  work  1-2-3-8  is  decreased  to  i  '-2 '-3 '-8  and  the 
refrigeration  is  increased  to  5/-4/-i'-6'.  The  same  effect  on 
work  is  noticed  if  the  lower  temperature  can  be  made  higher. 
Thus,  if  the  back  pressure  is  raised  to  i"-8",  then  the  work  is 
decreased  materially  and  there  is  an  increase  in  refrigeration. 
Hence  the  refrigerating  effect  is  increased.  Before  telling  the 
refrigerative  performance  or  the  cost  of  producing  ice  or  re- 
frigeration, the  temperature  range  must  be  known.  The  smaller 
the  range  of  temperature  the  more  effective  the  apparatus. 
Thus  7 1  tons  of  ice  per  ton  of  coal  is  often  reduced  to  6  and 
may  reach  15,  depending  on  the  temperature  ranges.  More- 
over, if  the  engine  driving  the  compressor  be  very  efficient, 
and  use  12  Ibs.  of  steam  per  H.P.  hour  instead  of  30  Ibs.,  the 
output  would  be  increased  very  materially.  Reports  have  been 
made  that  in  Europe  results  as  high  as  28  tons  of  ice  per  ton 
of  coal  have  been  obtained.  This  is  a  matter  of  temperature 
range  and  efficiency  of  engine.  In  many  cases  the  steam  of 
the  engine  is  used  to  give  distilled  water  for  ice  making,  and 
unless  evaporators,  which  complicate  the  apparatus,  are  used, 
a  low-grade  engine  is  required  to  give  the  necessary  amount 
of  water.  The  usual  amount  in  such  plants  is  6  to  9  tons 
of  ice  per  ton  of  coal.  If  raw  water  is  used,  then  an  engine 
of  greater  efficiency  may  be  used,  and  the  result  will  be  in- 
creased to  10  or  15.  With  a  gas-producer  engine  this  figure 
is  raised  to  20  tons  of  ice  per  ton  of  coal. 

The  common  form  of  absorption  apparatus  is  that  using 
aqua  ammonia.  Before  considering  the  operation  of  the 


80  ELEMENTS  OF  REFRIGERATION 

apparatus,  certain  physical  phenomena  must  be  noted  and 
quantitative  relations  given.  A  solution  of  30%  NHs  and 
70%  water  is  said  to  be  of  30%  concentration.  The  temperature 
at  which  a  solution  of  liquor  of  given  concentration  will  boil, 
depends  upon  the  pressure  on  the  liquor.  The  relation  between 
the  pressure  and  temperature  has  been  determined  experi- 
mentally by  Mollier  and  plotted  in  curves  and  tabulated. 
The  results  may  be  closely  approximated  in  the  form  of  an 
equation  similar  to  the  method  used  by  Macintire. 

rr\ 

~^  =  0.00471^  +  0.655 (80) 


7"^  =  temp,   of   saturated   ammonia   corresponding  to   the 

pressure; 
rsoi  =  temp.  of  boiling; 

x  —  per  cent  of  NHs  in  solution  =  per  cent  concentration. 
This  equation  has  been  derived  from  the  results  of  exper- 
iments of  Mollier  and  Perman  as  given  by  Lucke.  The  tabular 
values  given  do  not  give  uniform  changes  in  certain  increments, 
so  that  there  must  be  some  error  in  these  values.  The  equation 
will  give  results  within  i%  of  the  tabular  values. 

When  the  liquor  is  heated  to  drive  off  the  ammonia,  both 
ammonia  vapor  and  water  vapor  leave  the  liquor.  The  partial 
water  vapor  pressure  has  been  assumed  by  Spang] er  to  be  the 
steam  pressure  at  the  temperature  considered,  multiplied  by  the 
ratio  of  the  number  of  molecules  of  water  in  a  certain  amount 
of  liquor  to  the  total  number  of  molecules  of  liquor.  Thus 

—  =  relative  number  of  NHa  molecules, 
17 

—  =  relative  number  of  EbO  molecules. 

18 

Hence 

Partial  steam  pressure  =  p 

p  —  steam  pressure  at  given  temperature. 


x   -loo— #         1700+2 

~ 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    81 

The  values  given  by  this  method  of  computation  agree  well 
with  the  results  of  Perman  as  stated  by  Lucke. 

If  i  Ib.  of  ammonia  vapor  be  absorbed  by  200  Ibs.  of  water, 
it  will  be  found  that  893  B.t.u.  of  heat  are  developed.  This 
would  be  the  same  if  more  water  were  used,  and  it  is  called  the 
heat  of  complete  absorption.  If,  now,  a  smaller  quantity  of 
water  were  used,  it  would  be  found  that  less  heat  would  be 
liberated.  This  is  known  as  the  heat  of  partial  absorption. 
If  this  solution  be  added  to  enough  water  to  make  the  dilution 
one  in  two  hundred,  the  remaining  heat  of  the  893  heat 
units  would  be  liberated.  This  is  called  the  heat  of  complete 
dilution. 

Berthelot  has  found  that  the  heat  of  complete  dilution 
in  B.t.u.  is  142.5  times  the  weight  of  ammonia  per  pound 
of  water.  This  has  been  checked  by  Thomsen  with  a  wider 
range  of  experiments.  This  gives,  then 

Heat  of  complete  dilution  =  142.5- 


100  —  X 

This  gives  for  the  heat  of  partial  absorption 

&  =  893  -142.  5  —  -  —  .     .....     (82) 

IOO      X 

This  is  the  heat  when  i  Ib.  of  ammonia  is  dissolved  in 
sufficient  water  to  bring  the  concentration  to  x%. 

If  —  -  Ibs.  of  ammonia  are  absorbed, 

IOO 


fo    ^ 

(83) 


is  the  heat  generated  in  producing  i  Ib.  of  solution  of  strength 
x  by  adding  ammonia  to  water. 

The  amount  of  water  in   i  Ib.  of  mixture  of  strength  x  is 

IOO  —  X,  P  .       .          X 

•  --   and  the  amount  of  ammonia  is  —  . 

JOO  IOO 


82  ELEMENTS  OF  REFRIGERATION 


100— xr 


The  amount  of  water  is  -        — -,  and  the  ammonia  weighs 


100 


X 

if  the  i  Ib.  of  mixture  is  of  concentration  xf. 

loo 

The  amount  of  ammonia  to  bring  the  water  in  the  first 
case  to  concentration  x'  is 


_ 

IOO  —  X.  .   TOO     IOO  —  X  X' 


X 


IOO     ICO  —  X1   IOO  —  X' 


IOO 


or  the  additional  ammonia  to  change  strength  from  x  to  xf  is 


100  —  x  . .  x 


X— —  =  addition  of  NH3.      .     .     (84) 


IOO  —  X        IOO       IOO 


The  heat  produced  by  this  is  the  difference  in  the  two 
heats  of  partial  absorption. 


loo—  x      loo  loo  —  x 


If  this  is  divided  by  the  weight  added,  the  heat  per  pound 
of  NH3  added  to  change  the  strength  from  x  to  x'  is  given. 


.     .     (85) 


When  i  Ib.  of  ammonia  is  liberated  to  change  the  con- 
centration from  x'  to  x,  more  heat  is  required  than  that  given 
above,  because  the  water  vapor  is  driven  off  with  the  ammonia 
and,  moreover,  the  vapors  are  superheated  when  driven  off 
from  a  liquor. 

The  893  B.t.u.  is  the  heat  developed  from  the  absorption 
of  the  vapor.  If  a  liquid  is  used,  530.7  B.t.u.  above  32°  F. 
will  have  to  be  added  to  the  heat  to  care  for.  the  generation 
of  the  vapor.  This  would  mean  that  the  heat  developed 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    83 

would  be  less,  by  this  quantity,  if  liquid  ammonia  is  added 
to  water. 

The  specific  heat  of  aqua  ammonia  will  be  taken  as  unity. 

The  specific  gravity  of  aqua  ammonia  is  given  by 


Sp.gr.  =  i  —  4-3  \x~  *-+-*-  1  =S60     .    (86) 
loooL       100     10,000  J 

for  60°  F.     For  other  temperature, 


The  weight  of  weak  liquor  to  absorb  i  Ib.  of  ammonia  vapor 

and  change  its  strength  from  x  to  x'  is  given  as  follows: 


100  —  X 

—f 

x  —  x 


—  -y— 

100          100 
* 


PROBLEM  FOR  ABSORPTION  APPARATUS 

Suppose  the  water  available  for  cooling  is  at  60°  F.,  and  it 
is  desired  to  operate  the  absorption  machine  with  steam  at  5 
Ibs.  back  pressure. 

The  temperature  of  condensation  with  a  15°  rise  in  temper- 
ature of  the  cooling  water  and  a  10°  temperature  difference 
would  be  85°  F.,  and  this  would  give  an  absolute  pressure 
of  167.4  Ibs.  per  square  inch  for  the  ammonia.  The  pressure 
in  the  generator  to  allow  for  the  pressure  drop  in  the  separator, 
rectifier  and  analyzer  would  be  169  Ibs. 

The  temperature  corresponding  to  an  absolute  steam  pres- 
sure of  20  Ibs.  is  228°  F.  Allowing  6°  difference  in  the  coils  of 
the  generator  would  give  a  boiling  temperature  of  222°  F. 

The  minimum  concentration  under  169  Ibs.   and  222°  F. 
would  be  given  by  (80) : 


84  ELEMENTS  OF  REFRIGERATION 

If  higher  pressure  steam  were  available,  say  25  Ibs.  gauge, 
the  minimum  value  of  x  would  be  20.4%. 

8^.6+4^0.6 

,    ^      = 
267.2+459-6 

x  =  20.0%. 

This  would  increase  the.  ammonia  yield  and  cut  down  the 
amount  of  liquor  to  be  handled. 

If  the  cold  room  is  desired  at  o°  F.  with  a  10°  fall  in  the 
brine  temperature  and  10°  temperature  differences,  the  brine 
would  have  to  be  at  —20°  and  the  ammonia  in  the  expansion 
coil  would  be  at  —30°  F.  This  means  an  absolute  pressure  of 
13.56  Ibs.  per  square  inch.  The  absorber  pressure  would  then 
be  a  little  lower,  about  13  Ibs.  If  it  is  desired  to  get  a  solution 
of  40%  concentration  in  the  absorber,  the  limiting  temperature 
is  found  as  follows: 

-3I.5+4S9-6 


420.2  0 

^-=0.843, 

•L  sol 


Since  it  is  not  possible  to  maintain  this  temperature  with 
cooling  water  at  60°  F.,  a  lower  concentration  must  be  carried. 
Assume  that  a  temperature  of  80°  F.  could  be  maintained. 
Then 

428.1 

=  0.00471^+0.655, 


It  is,  of  course,  impossible  to  have  this,  as  the  absorber  would 
not  operate  to  give  the  proper  concentration. 

Suppose  then  that  a  5°  rise  is  permitted  in  the  brine  and 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    85 

5°  drop  in  heat  transfer.  This  would  mean  a  larger  brine  pump 
and  larger  coils.  The  temperature  of  the  ammonia  would 
then  be  —15°  F.,  and  the  pressure  would  be  20.46  or  20.00 
in  the  absorber. 

This  gives  for  40%  concentration. 


This  might  be  possible.     It  will  be  required,  however,  to 
use  70°,  which  gives,  as  the  limiting  value  of  xt 


The  amount  of  weak  liquor  allowed  to  flow  per  pound  of 
ammonia  absorbed  is,  by  (87) 


100  —  30.1 
y=-  -  =  7. 25  Ibs. 

39-I-30.7 


The  amount  of  strong  liquor  pumped  will  be  8.25  Ibs.  per 
pound  of  anhydrous  ammonia  absorbed  or  evaporated  in  the 
refrigerator  or  expansion  coil.  This  quantity  is  a  little  high, 
due  to  the  fact  that  the  limits  of  pressure  are  close.  The 
usual  practice  is  to  have  between  7  and  8  Ibs.  pumped  per 
pound  of  ammonia.  From  the  specific  gravity  of  aqua  ammonia, 
the  volume  of  the  liquor  for  a  given  amount  of  refrigeration 
could  be  found  and  from  this  the  displacement  of  the  pump. 

It  will  be  well  to  find  the  temperature  of  boiling  for  a  39.1% 
solution  under  the  pressure  of  the  analyzer  to  see  if  some  of 
the  liquor  will  boil  on  entering  this  part  of  the  system.  At 
the  top  of  the  analyzer  the  pressure  may  be  taken  as  168.5 
Ibs.  The  temperature  of  boiling  is  given  by 


rsol=  65o=  190.4°  F, 


86  ELEMENTS  OF  REFRIGERATION 

As  soon,  then,  as  the  strong  liquor  is  heated  to  191°  F., 
vapor  will  begin  to  come  off. 

Another  computation,  which  can  be  made  now,  is  the 
possible  rise  of  temperature  of  the  strong  liquor  in  passing 
through  the  interchanger;  8.25  Ibs.  of  strong  liquor  pass 
one  way,  while  7.25  Ibs.  of  weak  liquor  pass  the  other  way. 

If  the  efficiency  of  the  interchanger  is  assumed  to  be  90% 
and  the  strong  liquor  is  not  passed  to  the  rectifier  before  entering 
the  interchanger,  it  will  be  seen  that  the  interchanger  will  cool 
off  the  weak  liquor  so  that  there  is  no  need  of  a  weak  liquor 
cooler.  The  temperature  of  the  weak  liquor  entering  is  222° 
F.,  and  that  of  the  strong  liquor  is  70°.  The  weak  liquor  is 
assumed  to  be  cooled  to  76°  F. 


Radiation,  10%  =  105.8  B.t.u. 

Of  course,  if  76°  is  assumed  to  be  too  high  a  tempera- 
ture at  which  the  weak  liquor  enters  the  absorber,  with 
water  in  the  coil  at  60°,  this  may  be  cooled  down  to  65°  in 
a  weak  liquor  cooler  before  entering  the  absorber.  In  any 
case  this  heat  will  be  removed  by  the  cool  water  in  the 
absorber  cooling  coil  or  in  this  coil  and  the  weak  liquor  cooler 
coil  together. 

The  various  conditions  will  now  be  investigated,  starting 
with  the  entrance  into  the  condenser.  At  this  point  it  is  found 
by  some  engineers  that  the  best  results  are  obtained  if  the 
ammonia  is  superheated  about  20°  to  30°.  This  means  that 
the  temperature  of  the  ammonia  is  105°  F.  at  this  point  and 
that  the  total  pressure  is  167.4  Ibs.  The  strength  of  a  solu- 
tion boiling  under  these  conditions  is  given  by 


. 

=  0.00471^+0.655, 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     87 
By  (81)  the  partial  steam  pressure  is 


.. 

1700+65.5 

The  ammonia  vapor  pressure  =  167.  03  Ibs. 

The  saturation  temperatures  are  71°  and  84.9°,  given 
34°  F.  of  superheat  for  the  water  vapor  and  20.1°  for  the 
NH3. 

The  volume  of  i  Ib.  of  superheated  NH3  is  1.89  cu.ft.  and 
the  weight  of  the  superheated  steam  for  this  volume  is  about 
0.002  Ib.,  a  negligible  quantity. 

For  convenience  in  parts  of  the  problems  it  will  be  well 
to  tabulate  these  conditions  in  the  following  form: 

CONDITIONS  AT  ENTRANCE  TO  CONDENSER 

Concentration,  x  ..........................  .  65.5% 

Temperature  .............................  .  105°  F. 

Pressure  steam  ............................  Q-37 

Pressure  ammonia  .........................  167  .  03 

Saturation  temperature,  steam  ..............  71°  F. 

Saturation  temperature,  ammonia  ...........  .  84  .  9°  F. 

Superheat,  steam  ..........................  34°  F. 

Superheat,  ammonia  .......................  20.  i°  F. 

Specific  volume,  steam  ............  .  ........  893  cu.ft. 

Specific  volume,  ammonia  ...................  i  .  89  cu.ft. 

Heat  content,  steam  ........................  1108.0  B.t.u. 

Heat  content,  ammonia.  ...  .................  572  .8  B.t.u. 

Weight  of  water  vapor  per  Ib.  of  ammonia  ^-^  =  o.*oo2  Ib. 

842 

If  a  temperature  of  105°  F.  is  used  in  the  rectifier  the  water 
coming  from  the  condenser  at  70°  would  be  amply  cool  for  this 
work.  The  amount  of  supply  must  be  regulated  to  bring 
the  temperature  to  105°. 

The  vapors  entering  the  rectifier  will  be  assumed  to  be 
a  little  lower  than  185.5°,  as  the  rectifier  liquor  may  reduce 


88  ELEMENTS  OF  REFRIGERATION 

this  temperature.     Take   180°   as  the  first  assumption.     The 
pressure  here  may  be  168.5  Iks.  and  x  is  given  by 

85.4+4^9.6 

-^^-  =  0.00471^+0.655. 
180+459.6 


The  partial  steam  pressure*is 

1700  —  17X41.8 
*"7-SI        1741.8         =4'27' 

CONDITIONS  AT  ENTRANCE  TO  RECTIFIER 

Concentration  .............................  41.8 

Temperature  ..............................  180°  F. 

Pressure,  steam  ...........................  4-27 

Pressure,  ammonia.  .  .  ......................  164  .  23 

Saturation  temperature,  steam  ...............  155.  5°  F. 

Saturation  temperature,  ammonia  ............  83  .  9°  F. 

Superheat,  steam  ..........................  24.  5°  F. 

Superheat,  ammonia  .......................  96  .  i  °  F. 

Specific  volume,  steam  .....................  89  .  7  cu.ft. 

Specific  volume,  ammonia  ...................  2  .  29  cu.fL 

Heat  content,  steam  .................  .  ......  1  140  .  4  B.t.u. 

Heat  content,  ammonia  ....................  621  .4  B.t.u. 

Weight  of  water  vapor  per  Ib.  of  ammonia  —  —  =0.026  Ib. 

89.7 


It  is  seen  that  there  has  been  some  condensation  in  the 
rectifier,  as  the  moisture  per  pound  of  ammonia  at  entrance  is 
0.026  Ib.,  and  at  exit  it  is  0.002  Ib.  This  condensation  leads 
to  the  formation  of  liquor,  as  the  water  will  absorb  ammonia 
to  65%  concentration.  To  find  the  amount  of  ammonia  M 
entering  the  rectifier  the  following  equation  is  used  : 

[(0.026)  If  -0.002  X  i]—  =M—  i, 

*O  0 


.9516 


THERMODYNAMICS   OF  REFRIGERATING  APPARATUS     89 

The    absorption     of     0.045    Ik.    °f    ammonia    will    yield 

0.045  X— — =0.07  Ib.  of   solution   of   65%  concentration   and 

•65 
temperature  105°. 

The  moisture  with  1.045  Mbs.  °f  ammonia  is  1.045X0.026 
=  0.027  Ib. 

The  rectifier  has  the  following  weight  balance: 

Weight  Balance — Rectifier 
Entering : 

Ammonia  vapor 1 . 045  Ibs. 

Water  vapor 0.027 

1.072  Ibs. 
Leaving: 

Ammonia  vapor '.   i .  ooo  Ibs. 

Water  vapor o .  002 

Liquor o .  070 

1.072  Ibs. 

The  best  way  to  study  the  heat  required  in  any  part  of 
the  apparatus  is  to  find  the  sum  of  all  the  heats  entering  and 
leaving.  The  heat  entering  with  a  vapor  would  be  the  intrinsic 
energy  plus  the  work  done  in  forcing  the  vapor  in.  The  sum  of 
these  two  would  be  the  heat  content.  Where  there  are  several 
vapors  together,  the  sum  of  the  heat  contents  will  give  the 
heat  entering  or  leaving. 

For  liquids  the  heat  of  -the  liquid  must  be  considered.  In 
addition  the  heat  of  absorption  must  be  considered  as  a  neg- 
ative amount  of  heat,  because  the  heat  generated  by  this 
absorption  has  been  removed  before  the  solution  reached  this 
point.  Heats  are  figured  above  32°  F.  Absorption  experiments 
are  assumed  to  have  taken  place  at  68°  F.  Hence  the  heat 
content  of  ammonia  at  68°  must  be  added  to  negative  heat  of 
absorption  for  each  pound  of  ammonia  vapor  in  liquor.  514.7^ 
will  be  called  heat  of  absorbed  vapor. 


90  ELEMENTS    OF    REFRIGERATION 

The  sum  of  these  will  give  the  total  heat  at  any  point. 
Thus,  if  Maj  MSj  and  Mi  are  the  weights  of  ammonia  vapor, 
steam,  and  liquor,  and  the  strength  of  the  liquor  is  x,  the  fol- 
lowing is  the  scheme  for  the  heat  at  this  point: 
Energy  in  ammonia          —Mai\ 
Energy  in  steam  =Msi\ 

Heat  of  absorption  =  MA  8.930:  ---  -  -  —  )  ; 

\  100  —  x/ 

X 

Heat  of  absorbed  vapor    =  514.7^  —  ; 

100 

Heat  in  liquor  =MLqf. 

The  following  heat  balance  will  then  be  found: 
Entering:  Heat  Balance  —  Rectifier 

Energy  in  ammonia  ...................  1.045X621.4  =  649.0 

Energy  in  steam.  .  .  ..................  0.027X1140.4=  30.8 

679.8 
Leaving: 

Energy  in  ammonia  ..................  1.000X572.8=   572.8 

Energy  in  steam  ....................  0.002  X  1  108.0  =       2.2 

Heat  of  liquid  of  liquor  ............  0.07x005-32)  =       5.1 

580.1 
Heat  of  partial  absorption 


Heat  of  condensed  vapor  at  atmospheric  pressure 

=  0.045X514.7=    23.1 
Heat  removed  in  rectifier 

=  679.8  —  580.1  -f  28.3  —  23.1  =  104.9  B.t.u. 
Rectifier  cooling  of  water  from  68°  to  100° 

=  !?!^  =  3.27  ibs.  per  Ibs.  NH3. 

O 

Now,  if  8.25  Ibs.  of  liquor  of  strength  39.1%  be  mixed  with 
0.070  Ib.  of  strength  65%,  the  mixture  will  be  of  strength 
8.25X39.1+0.070X65^^^^ 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    91 

The  heat  generated  by  the  dilution  of  the  stronger  liquor 
and  the  concentration  of  the  weaker  is  given  by 


=  n.4  B.t.u. 
The  temperature  of  the  mixture  is  then  found  as  follows: 

^8.25X153.5+0-070X73  +  11.4^       o  F 
8.32 

/  =  i86.o°F. 

Although  1  80°  was  assumed  as  the  temperature  at  entrance, 
there  will  be  no  recomputation  of  this  point,  as  the  temperature 
1  86.0  may  be  decreased  by  radiation.  The  value  0.9  taken 
as  the  efficiency  of  interchange  is  not  known  close  enough  to 
warrant  recomputing  this.  The  temperature  of  the  liquor  of 
strength  39.3  will  be  taken  as  180°  F.  This  will  not  begin  to 
boil  until  it  reaches  a  lower  point  in  the  analyzer.  Extra  inter- 
changer  radiation  will  be  6.0X8.32  =  49.9.  In  the  analyzer  at 
the  upper  end  there  are  1.045  Mt>s.  °f  superheated  vapor  leaving 
with  0.027  Ib.  of  water  vapor,  and  entering  at  this  point  are 
8.32  Ibs.  of  liquor  of  39.3%  concentration.  At  the  lower  end 
of  the  analyzer  the  conditions  of  temperature  and  pressure  are 
as  follows: 

CONDITIONS  AT  ENTRANCE  TO  ANALYZER 

Boiling  temperature  .....................        222°  F. 

Concentration  ..........................         30  .  7% 

Pressure,  total  ..........................       169  Ibs. 


o^  o^- 

Steam  pressure  .......  17.86—  —  =     12.15 

1730.7 
Ammonia  vapor  pressure  ......  169  —  12.15   =   156.85 

Sat.  temp,  of  steam  .....................       202  .  5°  F. 


92  ELEMENTS  OF  REFRIGERATION 

Sat.  temp,  of  ammonia  ..................  81  .  i°  F. 

Steam  superheat  ........................  19.  5°  F. 

Ammonia  superheat  .....................  140.  9°  F. 

Volume  of  i  Ib.  of  ammonia.  .............  2.60  cu.ft. 

Volume  of  i  Ib.  of  steam  .................  33  .o  cu.ft. 

Heat  content,  ammonia  ..................  646.  2  B.t.u. 

Heat  content,  steam  .....................  1157.4  B.t.u. 

Weight  of  steam  with  i  Ib.  of  NHs  --52.  .  ..=       0.079  &• 

33-o 

In  passing  up  through  the  analyzer  the  vapor  is  changed, 
so  that  per  pound  of  NHs  passing  there  is  0.026  Ib.  of  water 
vapor  present  at  outlet.  The  original  amount  was  0.0785  Ib. 
of  vapor  per  pound  of  ammonia.  This  condensation  absorbs 
enough  ammonia  to  make  the  strength  41.8%.  By  the  method 
used  with  the  rectifier  the  amount  of  ammonia  absorbed  is 
0.04  Ib.  per  pound  of  ammonia  leaving,  and  the  amount  of 
liquor  formed  is  0.0957.  The  steam  condensed  is  0.0557  Ik. 

The  total  amount  of  ammonia  at  entrance  being  M,  the  fol- 
lowing holds: 

M  =  i.o4Jlf  Xi.045, 
If  =1.087. 


At  entrance  there  are  1.087  Mbs.  °f  NHs.  The  liquor  formed 
is  o.ioo  Ib.  Hence  the  liquid  dropping  back  into  the  analyzer 
will  be 

8.25  Ibs.  of  strong  liquor  of  strength  39.1%, 
0.07  Ib.  of  strong  liquor  of  strength  65%, 
o.ioo  Ib.  of  strong  liquor  of  strength  41.8%. 
This  gives  8.420  Ibs.  of  liquor  of  strength  39.3%. 

If  there  were  no  evaporation  in  the  analyzer,  this  liquid 
would  fall  into  the  generator,  but  because  there  is  heat  added 
to  liquor  by  superheated  vapors  passing  upward  some  ammonia 
is  driven  off.  Assume  that  the  temperature  of  the  liquor  is 
raised  to  192°  F.  There  must  be  a  balance  if  this  is  the 
case. 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    93 

CONDITIONS  AT  192°  F.  AT  BOTTOM  OF  ANALYZER 

Pressure  .................  .............       169  Ibs. 

Temperature,  assumed  ..................         192°  F. 

Concentration 

/85.6+459.6  \ 

\  192  +459.6  / 

1700-17X38.8 
Steam  pressure  ......  9r75—        Q  Q  —  =       5-84 

1735.5 

Ammonia  pressure  ............  169  —  5  .  84  =   163  .  16 

Saturation  temperature,  ammonia  ........  83  .  5°  F. 

Saturation  temperature,  steam  ..........  .  .  169°  F. 

Superheat,  ammonia  .................  ...  108  .  5°  F. 

Superheat,  steam  ......................         23°  F. 

Specific  volume,  ammonia  ............  ...  2  .  36  cu.ft. 

Specific  volume,  steam  ............  ......         66.3  cu.ft. 

Heat  content,  ammonia  .................  628  .  5  B.t.u. 

Heat  content,  steam.  ....  ...............     JI45-  5  B.t.u. 

•  2  "?6 

Weight  of  water  vapor  per  Ib.  of  NHs.  .  -^-  =         o  .  035 

06.3 

The  ammonia  set    free,  M,  in  changing    from    39.3%   to 
38.8%,  is  given  by 


(8.42  Xo.393-Af)        =  8.42  -I.035M, 


=  8.42(0.393-0.388)  =  0.542  = 
i  -(1.035)0.388       0.598 

The  amount  of  water  vapor  leaving  is 
0.070X0.035  =0.002. 

The  amount  of  liquor  falling  into  the  generator  equals 
8.42—0.070  —  0.002=8.348  Ibs. 

The  amount  of  ammonia  vapor  coming  from  the  generator 
amounts  to 

1.087—0.070  =  1.017  Ibs. 


94  ELEMENTS  OP  REFRIGERATION 

The  water  vapor  leaving  amounts  to 

1.017X0.079  =  0.080  Ib. 

The  weak  liquor  left  in  the  generator  is  equal  to 
8.348-1.097  =  7.251. 

This  should  mount  to  7.248,  since  0.002  Ib.  of    water   enters 
the  absorber  with  the  ammonia. 

Weight  Balance  for  Analyzer 
Entering: 

f  ammonia 1.017 

From  generator    \ 

{  water  vapor ....  o .  80 

From  rectifier,  liquor 070 

From  interchanger,  liquor 8 . 250 

9.417 
Leaving: 

_         ,.-       f  ammonia i  .045 

To  rectifier    \ 

(  water  vapor 0.027 

To  generator,  liquor 8 . 348 

9.420 

Heat  Balance  for  Analyzer 
Entering: 

ammonia.  1.017X646.2=  656.0 


From  generator  , 

[  steam.  .  .0.080X1157.4=     92.6 

From  rectifier  and  interchanger 

Heat  of  liquid  of  liquor  8.320X (180  —  32)  =  1230.0 


1978.6 
Heat  of  partial  absorption, 


=  —262O=  —262O 

Heat  of  absorbed  vapor 

8.32X0.393X5.147  =  1675 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     95' 

Leaving  : 

f  ammonia.   .1.045X621.4=   650 
To  rectifier  \ 

{  steam.  .  .  .0.027X1140.4=     30.9 

To  generator, 

Liquor,  heat  of  liquid  8.348[i92  —  32]  =  1335  .  o 

2015.9 
Heat  of  partial  dilution 


Heat  of  absorbed  vapor 

8.348X0.388X514.7  =  1662 

Heat  to  drive  off  ammonia  2620  —  2600  =  20  B.t.u. 
Excess  leaving  ........  2015.9-1978.6=  +37.3  B.t.u. 

Heat  of  atm.  pressure  ....  1662  —  1675  =  —  13  B.t.u. 

In  other  words  there  is  an  excess  of  44.3  B.t.u.  and  con- 
sequently the  liquor  cannot  be  warmed  to  192°. 

Try  188°. 

Pressure  ............................  169  Ibs. 

Temperature  assumed.  .  .  .  ............  188°  F. 

Concentration  .......................  39.9 

This  is  stronger  than  the  original  liquor,  so  there  can  be 
no  evaporation. 

Try  190°. 

Pressure  ............................  169 

Temperature  assumed  ................  190° 

Concentration  .......................   39.3 

This  is  possible,  as  the  liquor  is  just  heated  to  its  limit. 
Hence  all  will  fall  into  the  generator  giving  as  the  weight  balance 
the  following: 


96  ELEMENTS   OF   REFRIGERATION 

Weight  Balance  for  Analyzer 
Entering: 

From  generator, 

Ammonia i .  087 

Water  vapor o .  086 

From  rectifier  and  interchange^ 
Liquor 8 . 320 

9-493 
Leaving: 

To  generator,  liquor  (8.32+0.096) 8.420 

f  ammonia. . . , i .  0415 

To  rectifier 

[  steam 0.027 

9.492 

Heat  Balance 
Entering: 

f  ammonia. i. 087X646. 2=   703.0 
From  generator    \ 

{  steam.  .0.086X1157.4=     99.6 

From  rectifier  and  exchanger,  liquor 


2032.6 

Heat  of  partial  absorption =  —  2620.0 

Heat  of  absorbed  vapor  8.32X0.393X514.7  =  1685 
Leaving: 

To  generator,  liquor 8.42(190  — 32)  =  1330.0 

f  ammonia.  .  .  .1.045X621.4=  649.0 
To  rectifier    \ 

(  steam 0.027X1140.4=     30.8 

2009.8 

o     .  _ 

Heat  of  partial  absorption  -—*—  X  2620.0  =  —  2650 

8.32 

Heat  of  absorbed  vapor  8.42X0.393X514.7  =  1700 

There  are  22.8  B.t.u.  entering  in  excess  and  there  are  30 
B.t.u.  given  off  to  care  for  the  heat  in  large  amounts  of  liquor. 
To  allow  for  condensation  of  vapor  above  atmospheric  pressure, 
there  will  be  an  excess  of  15  B.t.u.  This  gives  37.8  B.t.u. 
in  excess.  This  would  raise  the  liquor  5  degrees,  but  this  is 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    97 

impossible  as  192°  is  too  high.     Suppose  190.8°  is  tried.     Since 
at  192  there  are  42.3  B.t.u.  in  excess  leaving,  and  at  190  there 
are  37.8  B.t.u.  in  excess  entering. 

Pressure  .............................       169 

Temperature  .........................       190  .  8 

Concentration  ........................         39.1 

Steam  pressure  ................  9.50^^  =       5  .  65 

Ammonia  pressure  ............  169  —  5.65  =  163.35 

Saturation  temperature,  ammonia  .......  83  .  5°  F. 

Saturation  temperature,  steam.  .  .  .......  167  .  5°  F. 

Superheat,  ammonia  ...................  107  .  3°  F. 

Superheat,  steam  .....................  23  .3°  F. 

Specific  volume,  ammonia  ..............  2.35 

Specific  volume,  steam.  ................  78.00 

Heat  content,  ammonia  ................  628  .  o 

Heat  content,  steam  ...................  1144.  9 


Lbs.  of  water  vapor  per  Ib.  of  NHs-=       0.030 

78.0 


NH3  set  free....  8.42  -^^  -     =       0.028 

\i- 1.030X0.3917 

Steam  set  free 0.028X0.030=       o.ooi 

Weight  Balance  of  Analyzer  ($d  Assumption) 
Entering: 

From  generator, 

Ammonia 1.085  —  0.028=       1.057 

Steam 0.086  —  0.001=       0.085 

From  rectifier  and  interchange^ 

Liquor 8 . 320 

9.462 
Leaving: 

To  generator,  liquor 8.420—0.029=       8.391 

f  ammonia =       i . 

To  rectifier 


9-463 


98  ELEMENTS  OF  REFRIGERATION 

Heat  Balance  for  Analyzer 
Entering: 

From  generator, 

Ammonia 1.057  =  646.2=       683.0 

Steam 0.085X1157.4=         98.5 

From  rectifier  and  interchange^  liquor. .  .  =     1230 


2011.5 
Heat  of  partial  absorption 


8,48,3x3,3-^-!  =  - 


2020 


Heat  of  absorbed  vapor 

8.32  Xo.393  X  514.?  =     1680 
Leaving : 

To  rectifier, 

Ammonia i  .045  X  62 1 .4  =       649 

Steam 0.027  X 1 140.4  =         30 . 8 

To  generator,  liquor.  .  .  .8.391(192.8  —  32)=     1330.0 


2009  .  8 
Heat  of  partial  absorption 


Heat  of  absorbed  vapor 

8.391X0.391X514.7=  1683 

Heat  of  absorbed  vapor  ......  1683  —  1680=  3  B.t.u. 

Heat  of  concentration  .......  2620  —  2620=  o  B.t.u. 

Excess  heat  leaving  ......  2009.8  —  2011.5=  —2.7  B.t.u. 

Excess  heat,  entering  ..................  =  0.3  B.t.u. 

If  190  gave  37.8  B.t.u.  excess  entering  and  190.8  gave 
0.3  B.t.u.  excess  entering,  the  value  of  190.85°  is  probably 
correct.  It  is  not  worth  working  as  close  as  this  and  tJ>£  37.8 
B.t.u.  excess  entering  may  be  assumed  to  be  cared  for  by  radia- 
tion, giving  the  second  computation  as  the  one  required. 

The  investigation  of  the  generator  now  follows. 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS     99 

Weight  Balance  for  Generator 
Entering: 

From  analyzer,  liquor 8 .420  Ibs. 


8.420  Ibs. 
Leaving : 

To  analyzer, 

Ammonia i .  087 

Steam 0.086 

To  exchanger, 

Liquor 7 . 248 


8.421 

Heat  Balance  for  Generator 
Entering : 

From  analyzer, 

Liquor 8.420(190  —  32)=     1330 

Heat  of  partial  absorption. =  —  2650 

Heat  of  absorbed  vapor 

8.416  Xo.393  X5I4-7  =     1?°° 
Leaving: 

To  analyzer, 

Ammonia 1.087  X646. 2  =       703 

Steam 086X1157.4=         99-6 

To  interchanger, 

Liquor 7.248(222.0  —  32]=     1378.0 


2180.6 
Heat  of  partial  absorption 


Heat  of  absorbed  vapor 

7.248X.307X5i4.7=     1149 

Heat  for  difference  in  heats  of  partial 
^absorption  ...............  2650—1845=       805 

Heat  excess  in  leaving  ......  2180.6  —  1330=       850.6 

Heat  in  atm.  pressure  .......  1149  —  1700=  —  551.0 

1104.6 


100  ELEMENTS  OF  REFRIGERATION 

Pounds  of  exhaust  steam  at  20  Ibs.  absolute  pressure,  of 
quality  0.85  required  to  produce  this  heat  is  given  by 

Lbs.  of  steam  =  -  —  —  =  i  •  3  S  Ibs. 
.85X961.7 

If  10%  radiation  is  assumed  the  steam  will  be  1.5  Ibs. 

At  the  discharge  of  the  condenser  at  85°  F.,  the  pressure 
is  167.4  Ibs.  and  the  strength  of  the  solution  that  can  be  formed 
is,  by  (80), 

1=0.00471^+0.655, 


This  result  is  large,  and,  moreover,  the  equation  is  not  true 
for  more  than  50%  concentration.  The  condition  of  the  liquor 
is  not  known.  The  quantity  formed  in  any  case  is  not  large, 
so  it  will  be  assumed  that  the  strength  is  70%,  and  hence  on 
the  condensation  of  0.002  Ib.  of  water,  the  liquor  formed  will 
be  0.005  Mb.  This  gives  the  following  weight  balance. 

Weight  Balance  for  Condenser 
Entering: 

From  rectifier, 
Ammonia  ............................   i  .  ooo 

Steam..  ,  .  0.002 


i.  002 
Leaving : 

To  throttle  valve, 

Liquid  NH3 o .  997 

Liquor 0 . . , o .  005 


i.  002 
The  heat  balance  is  as  follows: 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS   101 

Heat  Balance  for  Condenser 
Entering: 

From  rectifier, 

Ammonia 1.000X572.8  =  572.8 

Steam.  ..0.002X1108.0=     2.2 


575-0 
Leaving 

To  throttle  valve, 
Liquid  ammonia  ..........  0.997X59.4=   59.2 

Liquor  .................  0.005(85-32)=     0.3 

Heat  of  partial  absorption 


Heat  of  absorbed  vapor.  .  .  0.003  X5i4-7=     1.5 

59-3 
Heat  removed  ........  ...  .575-°-59-3  =  5I5-7  B-t.u. 

Lbs.  of  water  heated  from  60  to  75°  per 
Ib.  of  ammonia  entering  condenser 


(If  water  from  68°  to  75°  is  used,  the  amount  required  will 
be  73.7  Ibs.,  or  the  water  from  the  absorber  could  be  used  in 
the  condenser.) 

EXPANSION  OR  THROTTLE  VALVE  AND  EXPANSION  COIL 

NOTE.—  No  radiation  is  assumed  from  receiver. 

This  action  is  constant  heat  content  action.  Hence  i  after 
expansion  is  that  for  the  liquid  at  85°  or  59.4  B.t.u.  The  heat 
content  for  dry  ammonia  at  —15°  is  534.3  B.t.u.  Hence  the 
refrigeration  produced  is  equal  to 

0.997(534.3  -  59.4)  -0.005(85  -  (  -  15)]  =  472.9. 

If  10  B.t.u.'s  are  assumed  for  leakage,  this  gives  462.9  B.t.u. 
of  heat  abstracted  in  the  expander  per  pound  of  ammonia 
entering  the  condenser. 


102  ELEMENTS  OF  REFRIGERATION 

The  number  of  pounds  of  ammonia  per  minute  per  ton 

of  refrigeration  is 

100.2  „ 

0.430  Ib. 


462.9 

ABSORBER 

Weight  Balance  for  Absorber 
Entering: 

From  expander, 
Ammonia  .....................  o  .  997 

Liquor  ........................   o  .  005 

From  interchanger, 

Liquor  ........................   7  .  248 

-  8.250 
Leaving: 

To  interchanger, 

Liquor  ........................  8  .  250 

-  8.250 
Heat  Balance  of  Absorber 

Entering: 

From  expander, 

Ammonia  .............  .  .  .  0.997  X  534.3  =  532-8 

Liquor  ..............  o.oo5X(-iS-32)  =  -°-2 

Heat  of  partial  absorption 

[142.5X70] 
893  --  L^.^-Ly 

Heat  of  absorbed  vapor  ...............  =     1.5 

From  interchanger, 

Liquor  ................  7.248X(76~32)  =319.0 

Heat  of  partial  absorption  .............  =  —  1845 

Heat  of  absorbed  vapor  ...............     1  149 

Leaving: 

To  interchanger, 

Liquor  .................  8.25X(7o~32)  =313 

Heat  of  partial  absorption 


Heat  of  absorbed  vapor 

8.25X0.391X514-7  =  1658 


THERMODYNAMICS  OF  REFRIGERATING  APPARATUS    103 

Heat  entering  —  heat  leaving 

=  [532.8-0.2+319-313] 

+  [2580-  1845  -i.  7]  -[1658-  1149-  1.5] 

=  538-6  +  733.3-  507-5  =  764-4  B.tu. 

If  60°  water  enters  and  is  raised  to  68°  F.  in  the  cooling 
coil,  the  cooling  water  required  will  be 

=95-42lbs.  per  Ib. 


This  is  excessive  and  in  practice  a  greater  range  of  tem 
perature  would  be  used.     This  would  reduce  the  quantity. 

Work  of  Pump 
The  work  done  in  the  pump  is  given  by 


- 

778 


(169  —  20.00)  144  X8. 25 


=  4.18  B.t.u. 

This  heat  is  added  by  the  pump  and  is  cared  for  by  radi 
ation.     The  following  heat  balance  is  made: 


Generator 

1104  6 

Analyzer 

11  8 

Rectifier  

103  i 

Condenser 

CIC    7 

Expander 

4.62  o 

—  IO   O 

Absorber  

764  4 

Pump. 

A     2 

Interchanger  

f  105.8 

•j      4.2  (pump) 

I    49-9(P-  9i) 

i57i-7 

1383.2 
187.7 

1570.9 

187.7 

104 


ELEMENTS  OF  REFRIFERATION 


If  i|  tons  of  refrigeration  are  required  per  ton  of  ice,  this 
apparatus  would  require 

1.5X0.43X24X60  =  930^8. 

of  ammonia  entering  the  condenser  per  day. 

The  steam  needed  for  this  would  be  930X1.4  =  1305  Ibs. 
This  would  require  the  exhaust  of  a  21  H.P.  engine  to  supply 
the  steam 


\24X30 
If  the  steam  were  supplied  by  a  boiler,  the  coal  required  would 


be          =  130.5  Ibs.     The  ice  per  pound  of  coal  would  be 


10 


2000 


=  15.3  Ibs. 


In  practice  these  plants  yield  from  9  to  10  tons  of  ice  per 
ton  of  coal  supplied.  In  a  test  by  N.  H.  Hiller,  60  tons  of  ice 
required  3890  Ibs.  of  steam  per  hour.  Assuming  that  this  high 
pressure  steam  is  made  at  the  rate  of  8  Ibs.  per  pound  of  coal, 
the  coal  required  for  60  tons  of  ice  would  be  11,670  Ibs.  or  5.8 
tons.  This  gives  a  value  of  10.3  tons  of  ice  per  ton  of  coal. 
The  steam  used  for  this  apparatus  could  have  been  the 
exhaust  steam  from  an  engine,  and  consequently  the  full  coal 
should  not  be  charged  to  ice-making. 

To  give  some  comparative  figures  from  the  problems  in  this 
chapter,  the  results  have  been  collected  in  the  following  table: 


| 

o 

| 

| 

S,  o   , 

M 

°l 

1 

c  is 

d 

g 

+*    IH    o 

•*•*   In 

tu  o 

*9 

II 

I 

be  v 

o  d 

4-»     5j 

2J 

+•*  w 

||| 

<^  afe 

111 

I! 

s§ 

d 

H  2 

S  o 

w  C  C 

«8  C  ft 

IH    . 

w 

8  o 

>  o 

^ 

w 

3° 

r^ 

3fc 

5^C 

5^P 

w 

^ 

^ 

F. 

F. 

Lbs. 

Air  atmospheric  

—  10 

70 

58.8 

14.  .  7 

103  .  9 

82    2 

4   05 

24.4 

o  95 

Air  dense  

—  IO 

7° 

235  .  2 

58.8 

26.0 

2O.5 

4.O5 

24.4 

o.  95 

Ammonia  wet 

—  25 

80 

152     Q 

15  6 

8  o 

I   42 

252 

3  32 

Ammonia  dry           .... 

—  25 

80 

J53  -9 

15.6 

7  o 

1.58 

25.9 

2.06 

CO2  wet   

—  25 

80 

967.0 

2OI  .  1 

1.76 

2.96 

^O.O 

2.48 

SO2,  wet  

-25 

80 

59-7 

5-0 

22.7 

1-43 

25-3 

3-31 

THERMODYNAMICS   OF  REFRIGERATING  APPARATUS     105 

The  refrigerant  to  be  used  is  determined  by  the  designer 
of  the  plant.  Each  has  certain  advantages.  Air  is  the  cheapest 
of  all,  but  jts  properties  are  such  that  large  displacements 
are  necessary,  even  with  dense-air  machines,  and  for  ordinary 
temperature  ranges  the  refrigerating  effect  is  small.  Sulphur 
dioxide  and  ammonia  are  objectionable  on  account  of  danger 
to  life  and  property  in  case  of  breaks  in  the  system.  Carbon 
dioxide  is  not  objectionable  from  this  cause.  The  C02  and 
SO2  are  much  cheaper  than  ammonia;  when  the  pressure  range 
is  considered  it  is  found  that  carbon  dioxide  requires  excessive 
pressures  on  both  sides  of  the  system,  thus  necessitating  steel 
cylinders,  special  packings,  heavy  piping  and  fittings,  but  a 
small  size  compressor.  The  pressures  with  sulphur  dioxide  are 
not  great  and  with  ammonia,  although  the  pressure  is  high 
on  the  upper  side,  it  is  not  so  high  as  to  require  special  con- 
structions. The  sulphur  dioxide  compressor  is  large  as  com- 
pared with  the  ammonia  compressor.  Carbon  dioxide  is  near 
the  critical  temperature  at  ordinary  water  temperatures,  and 
this  causes  certain  changes  to  be  made.  As  was  shown  on 
Fig.  33,  this  substance  may  be  operated  above  the  critical 
point.  Ammonia  is  the  most  common  substance  employed, 
but  there  is  a  tendency  to  use  carbon  dioxide  to  a  greater 
extent  than  formerly. 

Experimental  runs  have  shown  that  these  substances  give 
about  the  same  practical  results.  The  SCb  and  NHs  corrode 
metals  slightly  and  C02  and  SO2  machines  being  nearer  than 
NHs  to  their  critical  temperatures,  will  not  cause  excessive 
pressure  if  the  condenser-water  should  fail,  as  has  happened 
with  NHs,  causing  rupture  in  the  system.  NHs  with  oil  forms 
a  combustible,  which  cannot  be  said  of  862  and  CO2.  Carbon 
dioxide  can  be  brought  in  contact  with  any  metal,  while  NHs 
and  862  must  be  kept  in  contact  with  iron  and  steel  only. 

Mixtures  of  CO2  and  862  have  been  tried. 

Methyl  and  ethyl  alcohol  and  methyl  chloride  have  been 
used  as  refrigerants. 

In  refrigeration,  2  gals,  of  water  per  minute  are  generally 
required  per  ton  of  refrigeration. 


106 


ELEMENTS  OF  REFRIGERATION 


The  effect  of  temperature  range  is  seen  by  the  following 
table,  given  by  Thomas  Shipley  in  the  Bulletins  of  the  York 
Manufacturing  Co.: 

VOLUMETRIC  EFFICIENCY,  DISPLACEMENT  PER  MINUTE  PER  TON  AND  COMPRES- 
SOR HORSE-POWER  PER  TON  FOR  YORK  SINGLE-ACTING  COMPRESSOR. 


Suction  Pressure  and  Temperatures  of  Saturation. 

High  Pressure  by 
Gauge  and  Temp,  of 

5  Lbs.  Gauge  or 
-17-5°  F." 

10  Lbs.  Gauge,  or 
-8.05°  F. 

15.67  Lbs. 
oc 

Gauge  or 
F. 

Saturation. 

Disp. 

Disp. 

Disp. 

Vol. 
Eff. 

per 

Min. 

I.H.P. 

Vol. 
Eff. 

Min. 

I.H.P. 

Vol. 
Eff. 

per 

Min. 

I.H.P. 

Cu.ft. 

Cu.ft. 

Cu.ft. 

145  Ibs.,  82°  F  

0.79 

7.28 

1.65 

0.812 

5.  7 

i  .4 

0.83 

,1 

.5 

I  .  2 

165  Ibs.,  89°  F.  .  ... 

0-775 

7-5 

1-83 

0.797 

5-9 

1.56 

0.815 

4 

.6 

i-34 

185  Ibs.,  95-5°  F.... 

0.76 

7.8 

2  .OI 

0.782 

6.0 

1.72 

0.80 

4 

.8 

1.49 

205  Ibs.,  101.4°  F..  . 

0-745 

8.05 

2.19 

0.767 

6.2 

1.89 

0.785 

S 

.0 

1-63 

Suction  Pressures  and  Temperatures  of  Saturation. 

High  Pressure  by 
Gauge  and  Temp,  of 

20  Lbs.  Gauge  or  5.7°  F. 

25  Lbs.  Gauge  or  11.5°  F. 

Saturation. 

Vol.  Eff. 

Disp.  per 

Min. 

H.P. 

Vol.  Eff. 

Disp.  per 

Min. 

H.P. 

Cu.ft. 

Cu.ft. 

145  Ibs.,  82°  F  

0.842 

3.9 

1.  06 

0.855 

3-4 

0.94 

165  Ibs    89°  F 

0.827 

4-i 

1  .  2O 

0.84 

3-5 

1.07 

185  Ibs.,  95.5°  F.... 

0.812 

4.2 

i-34 

0.825 

3-6 

1.20 

205  Ibs.,  101.4°  F.  .  . 

0.797 

4-3 

1.47 

0.81 

3-7 

1.32 

From  the  above  table  it  is  seen  that  the  range  of  temper- 
ature has  a  great  effect,  the  variation  in  the  table  being  from 
2.19  H.P.  per  ton  to  0.94  H.P.  per  ton.  It  is  absolutely  nec- 
essary to  know  conditions  before  a  given  problem  can  be 
solved.  The  smaller  the  range  of  temperature,  the  less  the 
H.P.  required.  The  table  has  been  based  on  tests  made 
on  compressors  with  a  clearance  of  not  more  than  y^"  and 
with  no  after  cooling.  With  after  cooling  there  would  be  a 
reduction  in  horse-power.  To  find  the  engine  horse-power, 
an  allowance  of  17%  must  be  added  for  small  compressors, 
and  15%  for  large  compressors  to  care  for  friction. 

To  utilize   the  fact  that  small   temperature  range  means 


THERMODYNAMICS   OF  REFRIGERATING  APPARATUS     107 


an  increase  of  efficiency,  Mr.  G.  T.  Voorhees  patented  the 
application  of  multiple  effect  to  absorption  and  compression 
machines,  when  different  temperatures  are  applicable  on  the 
lower  side  of  the  system.  The  compressor  system  and  absorber 
system  are  shown  in  Fig.  35.  In  this  system  the  vapor  from 
the  compressor  or  rectifier  is  sent  to  the  condenser  and  after 
it  passes  a  throttle  valve  to  reduce  its  pressure  to  a  point  above 


1st  Throttl 


Brine  Cooler 
24°F. 


Pump    Inter  changer 

-<> 

H.P.  Absorber      IT,. P.  Absorber 


--=Z^r-     L     =Tir=i=  15  Lb. 


Brine  Cooler 
2i°F. 


FIG.  35. — Voorhees  Multiple  Effect  Apparatus. 

the  lowest  pressure  used,  it  is  caught  in  a  receiver  called  by 
Voorhees,  a  multiple  effect  receiver.  From  the  receiver  some 
of  the  liquid  may  pass  without  throttling  to  a  brine  cooler, 
and  the  evaporation  from  this  passes  back  into  the  receiver. 
Some  of  the  liquid  from  the  receiver  is  passed  through  another 
throttle  valve  and  is  delivered  at  a  lower  pressure  to  another 
brine  cooler  or  refrigerating  coil.  The  low  pressure  in  this 
coil  is  maintained  by  a  compressor  or  by  an  absorber  of  low 
pressure.  In  the  case  shown  in  the  figure,  the  absolute  pres- 


108  ELEMENTS  OF  REFRIGERATION 

sure  is  about  15  Ibs.  per  square  inch.  The  vapor  formed  in 
the  receiver  from  the  evaporation  in  the  first  cooler  and  from 
the  throttling  of  the  liquid  in  the  first  expansion  valve  is  taken 
to  an  absorber  of  37  Ibs.  absolute  pressure  in  one  case,  or  to  a 
cavity  at  the  end  of  the  stroke  of  the  compressor,  so  that  when 
the  piston  overrides  a  port  at  the  end  of  the  stroke,  this  vapor 
at  37  Ibs.  pressure  will  flow  in,  since  the  pressure  inside  of  the 
compressor  at  the  end  of  the  suction  stroke  is  slightly  less 
than  15  Ibs.  The  ammonia  is  now  compressed  and  the  cycle 
is  followed  out  again.  The  card  from  the  compressor  is  seen  in 
Fig.  32.  In  the  absorber,  the  low-pressure  absorber  receives 
the  weak  liquor  from  the  interchanger  and  delivers  a  stronger 
liquor  through  the  pump  to  the  high-pressure  absorber,  and 
this  delivers  its  strong  liquor  to  the  analyzer  through  the 
interchanger. 

The  purpose  of  these  two  inventions  is  to  utilize  different 
ranges  of  temperature  where  possible,  as  the  efficiency  may  be 
increased.  In  cutting  down  the  range  for  part  of  the  opera- 
tion, this  part  is  done  more  efficiently  and  consequently  the 
total  effect  is  better. 

There  are  many  cases  in  which  there  is  some  cooling  at 
a  higher  temperature  than  another,  and  whenever  that  is  so, 
this  method  can  be  used.  Thus,  to  reduce  the  temperature 
of  water  to  40°,  brine  at  a  higher  temperature  than  that  required 
to  freeze  the  water  could  be  used.  If  certain  rooms  are  re- 
frigerated to  35°  while  others  are  at  20°,  this  method  could  be 
employed.  One  of  the  latest  applications  is  by  the  Quincy 
Market  Cold  Storage  Co.,  of  Boston,  in  their  new  looo-ton 
compressor,  the  largest  ever  built.  This  compressor  draws 
ammonia  from  two  systems,  the  cold-storage  system  of  low 
pressure  and  the  conduit  system  at  a  higher  pressure. 


CHAPTER  IV 
TYPES  OF  MACHINES  AND    APPARATUS 

THE  compressor  is  the  important  part  of  refrigerating 
apparatus.  Fig.  36  shows  a  section  through  the  housing  of  a 
York  compressor.  The  driving  of  these  compressors  is  accom- 
plished by  an  engine  or  electric  motor.  The  former  is  shown 
in  Fig.  14.  Fig.  36  shows  a  section  through  both  cylinders. 
As  is  true  in  most  large  vertical  compressors,  the  two  com- 
pressors are  connected  to  a  common  shaft  with  cranks  at  right 
angles.  One  steam  cylinder  is  usually  employed.  This  is  hori- 
zontal and  is  connected  to  one  of  the  two  crank  pins.  The 
form  of  housing  is  clearly  indicated  by  Figs.  14  and  36.  The 
housings  must  be  solid  and  of  proper  section  to  make  a  rigid 
construction.  The  box-girder  columns  are  connected  at  the 
bottom  by  the  casting  which  carries  the  main  bearing  and  gives 
a  very  strong  form.  The  working  platforms  for  large  machines 
are  carried  from  the  housing  or  frame.  The  fly-wheel  is  placed 
between  the  cylinders,  being  supported  in  a  simple  manner  by 
the  two  bearings. 

The  cylinders  are  built  as  shown  in  the  figure.  They  are 
single  acting  and  are  made  of  close-grain  metal.  The  suction 
enters  at  the  bottom  of  the  cylinder  on  the  up-stroke  of  the 
piston.  The  piston  is  made  long  and  has  four  piston  rings 
to  give  tightness.  The  piston  casting  is  carried  by  a  spider  and 
hub  so  that  the  ammonia  may  pass  through  the  suction  valve 
at  the  center  of  it.  This  valve  has  a  central  spindle  to  which 
is  attached  a  cushion  head.  This  is  a  plate.  A  projecting 
cup  carried  by  a  spider  from  the  removable  seat  receives  the 
plate.  This  plate  and  cup  fit  so  closely  that  they  form  a  dash 
pot  and  prevent  the  hammering  of  the  valve  and  limit  its  motion. 
A  spring  is  also  used  to  aid  in  supporting  the  valve. 

109 


110 


ELEMENTS  OF  BEFRIGERATION 


The  gas  is  sucked  into  the  upper  end  on  the  down-stroke 
of  the  piston,  and  when  the  compressor  reverses,  the  valve  is 
closed  and  the  ammonia  is  compressed  until  the  pressure 


FIG.  36. — Cross-section  of  York  Compressor. 

beneath  the  valve  at  the  center  of  the  head  is  greater  than 
the  pressure  above.  As  will  be  seen,  this  valve  is  controlled 
by  a  small  spring  on  top  of  it,  but  the  dash  pot  into  which 
a  cylindrical  projection  on  the  back  of  the  valve  fits,  pre- 


TYPES   OF  MACHINES  AND  APPARATUS 


111 


Water  Overflow 


FIG.  36a.— Sectional  View  of  York  Compressor. 


112  ELEMENTS  OF  REFRIGERATION 

vents  this  spring  from  slamming  the  valve  down  on  the 
seat.  As  is  the  case  with  the  suction  valve,  the  valve  seat 
is  removable.  The  working  head  of  the  cylinder  is  not 
bolted  to  the  cylinder  flange,  but  is  held  down  by  heavy 
springs  pressing  against  the  outer  head,  which  is  bolted  fast 
to  the  cylinder.  The  joint  between  the  outer  head  and 
flange  is  made  tight  by  a  lead  gasket  in  a  groove  on  which 
a  ring  projecting  from  the  head  presses.  The  purpose  of 
the  inner  head  is  to  eliminate  the  danger  resulting  from  the 
small  clearance  used  in  these  compressors.  The  piston  is  brought 
up  so  that  it  practically  touches  the  cylinder  head.  Any 
incorrect  adjustment  of  connecting  rod,  or  the  presence  of  scale 
would  force  the  piston  against  the  head  and  break  off  the 
cylinder  were  it  not  for  this  yielding  safety  head. 

The  stuffing-box  is  long  and  contains,  in  addition  to  the 
large  amount  of  packing,  a  lantern  of  metal  through  which  oil 
can  be  forced  on  the  rods.  This  lantern  is  composed  of  two 
rings  connected  by  bars  at  intervals.  A  long  bushing  or  gland 
presses  against  the  soft  packing.  The  cap  presses  this  and  is 
screwed  on  the  box  by  means  of  a  gear  wheel,  the  shaft  of  which 
is  led  to  a  convenient  point  for  operation.  The  lower  part  of 
the  cylinder  is  a  separate  casting  to  simplify  construction. 

The  thin  sheet-metal  cylinder  covered  with  wood  lagging 
and  bolted  to  a  large  flange  at  the  lower  end  of  the  cylinder 
casting  forms  a  water  jacket  for  the  removal  of  some  of  the 
heat  of  compression.  It  does  remove  some  heat  and  so  reduces 
the  work  of  compression,  but  the  amount  is  not  large.  The 
York  Company  has  experimented  and  found  that  the  jacket 
as  originally  made  is  not  an  element  of  gain,  and  for  that 
reason  their  later  jackets  are  placed  only  at  the  upper  end  of 
the  vertical  cylinder.  If  heat  is  removed  at  all  by  the  jacket 
there  should  be  a  gain.  It  may  have  been  that  the  lower 
part  of  the  jacket  warmed  the  incoming  gas  and  cut  down 
the  weight  taken  in,  but  as  stated  above,  if  the  jacket  re- 
moves any  heat  it  should  be  an  element  of  economy. 

All  parts  of  this  cylinder  and  piston  are  easily  accessible. 
This,  together  with  the  facts  that  there  is  no  bottom  wear  or 


TYPES  OF  MACHINES  AND  APPARATUS  113 

friction  on  the  cylinder  and  stuffing-box,  from  the  piston  and  rod, 
in  the  vertical  position,  and  that  there  is  no  stuffing-box  exposed 
to  high  pressure,  has  led  to  the  selection  of  a  vertical  single- 
acting  compressor.  The  stuffing-box  does  not  require  such  tight 
packing  and  this  reduces  the  friction.  In  a  double-acting  com- 
pressor it  would  be  difficult  to  use  safety  heads,  and  so  the 
clearance  must  be  greater.  Of  course  this  does  not  increase  the 
work  of  compression  except  for  friction,  but  it  does  cut  down 
the  volumetric  efficiency,  requiring  a  slightly  larger  cylinder. 
The  use  of  two  cylinders,  whether  of  double  or  of  single  action, 
is  advantageous  in  that  if  one  must  be  disconnected  for  repair, 
the  other  may  be  operated  alone  and  the  plant  kept  in  operation. 


FIG.  37. — Indicator  Card  from  Compressor  with  Guide  Lines. 

Fig.  37  shows  an  indicator  card  taken  from  such  a  com- 
pressor. If  the  clearance  line,  absolute  zero  line,  suction-pressure 
line  and  discharge-pressure  line  are  drawn  on  this  card  and  then 
the  adiabatic  is  constructed  as  shown  by  the  method  below, 
certain  information  may  be  had  in  regard  to  the  operation 
of  the  compressor  in  addition  to  the  knowledge  of  the  power 
taken.  The  horse-power  is  worked  out  in  the  usual  manner. 

If  the  suction-pressure  line  is  much  above  the  back-pressure 
line,  there  is  excessive  valve  friction  due  to  the  spring  being  too 
tight  or  the  valve  sticking.  If  the  discharge  pressure  is  much 
below  the  upper  pressure  of  the  card,  the  same  may  be  said  of 
the  discharge  valve.  If  the  adiabatic  falls  below  the  compres- 
sion line,  there  must  be  a  leaky  discharge  valve,  while  a  com- 
pression line  below  the  adiabatic  would  mean  a  leaky  suction 


114  ELEMENTS  OF  REFRIGERATION  \ 

valve  or  piston.  The  jacket  does  remove  heat  and  causes 
the  compression  line  to  fall  below  the  adiabatic  line  in  theory, 
but  this  amount  is  so  small  that  it  can  hardly  be  noticed  on  the 
card.  Hence,  when  there  is  a  decided  drop  below  the  adiabatic, 
which  is  what  is  desired  in  theory,  one  must  look  for  a  leaky 
piston  or  suction  valve,  as  the  ordinary  jacket  could  not  pro- 
duce the  result. 

The  construction  of  the  adiabatic  is  one  which  would  have 
to  be  made  by  use  of  an  equation  of  the  form 

pvn  =  const.      .     ......     (i) 

If  the  compression  is  dry,  the  adiabatic  is  of  the  form 

#»1-33  =  const.     .......     (2) 

For  wet  compression  the  value  of  n  must  be  computed 
for  any  given  condition.  The  conditions  at  the  ends  of  com- 
pression must  be  known.  The  quality  x  at  one  end  is  related 
to  that  at  the  other  by  the  equation 

/      ,  OC\r\         f        X2T2  f   N 

Si+^r~=S2+-^-  .......     (3) 

1  1  ±2, 

s'  =  entropy  of  the  liquid  ; 
Tp:  =  entropy  of  vaporization; 
x  =  quality. 

In  this  x\  may  be  found  from  X2  since  the  two  pressures  are 
known,  or  as  is  usually  the  case,  X2  is  made  unity  and  then 


f  x 

(4) 


Having  x\  and  X2  the  volumes  per  pound  may  be  found  by 

VI  =  XIV"L      .    '.    .   •.    .     .     .     (5) 

V2  =  X2V"2.         ..,«.,.      (6) 


TYPES  OF  MACHINES  AND  APPARATUS 

v  =vol.  of  i  Ib.  of  mixture; 
•o"  =  vol.  of  i  Ib.  of  dry  vapor. 

Then  n  is  given  by 

log^-2 


115 


log 


(7) 


After  the  n  for  wet  compression  is  found,  the  equation  is 
known.  Having  the  values  of  n,  the  volume  vi  from  the  zero 
volume  line  and  the  pressure  pi  from  the  zero  pressure  line 
are  measured  in  inches  and  then  by  assuming  other  volumes  the 
pressures  at  those  points  may  be  found  by 


n  log  vx 
These  are  tabulated  for  ^  =  1.33  for  the  card. 


(8) 


Point                  

i 

a 

b 

c 

Volume  in  inches  

2.16 

i  .20 

0.80 

O.7O 

Pressure  in  inches 

o  24 

o  ^3 

O.QO 

I  .  !•? 

The  motor  driving  the  compressor  may  be  one  of  various 
types.  For  large  compressors  efficient  Corliss  engines  are  used 
for  refrigeration,  although  for  ice-making  where  distilled  water 
is  needed,  less  efficient  engines  are  used.  Gas  engines  are  used 
at  times  and  electric  motors  are  of  great  value  for  small  plants 
in  hotels,  hospitals,  stores  and  residences. 

One  of  the  early  successful  ammonia  compressors,  used  in 
the  days  of  the  introduction  of  mechanical  refrigeration,  which 
has  remained  one  of  the  leading  compressors,  is  that  built  by 
the  de  La  Vergne  Machine  Company.  The  cylinder  of  their 
vertical  type  is  shown  in  Fig.  38.  This  is  their  vertical  double- 
acting  compressor.  The  head  of  the  cylinder  contains  several 


116 


ELEMENTS  OF  REFRIGERATION 


FIG.  38. — De  La  Vergne  Vertical  Double-acting  Cylinder. 


TYPES  OF  MACHINES  AND  APPARATUS  117 

delivery  valves  placed  in  a  casing.  The  suction  valves  are 
placed  in  casings  inserted  in  the  sides  of  the  cylinder.  Each 
valve  is  held  to  the  seat  by  means  of  a  spring  and  is  arranged 
to  be  guided  by  a  long  sleeve  around  a  central  spindle.  This 
forms  a  dash-pot  action  and  prevents  slamming.  The  suction 
valves  are  in  cages  forced  into  radial  recesses  in  the  cylinder. 
By  removing  the  cover  of  the  recess,  the  valves  and  their  seats 
may  be  removed  for  examination  or  repair  since  the  valve 
cages  include  valves,  seats,  springs,  and  dash  pots.  The  head 
discharge  valves  are  placed  in  a  casing  or  housing.  This  is  held 
against  a  projecting  part  of  the  cylinder  casting  making  a  gas- 
tight  joint  by  the  head  pressure  in  addition  to  the  pressure  from 
a  set  screw  attached  to  the  main  head  of  the  cylinder.  This 
set  screw  has  a  jamb  nut  on  it  and  to  care  for  the  ammonia 
leakage  around  the  threads,  a  cap  is  fastened  over  the  top. 
This  cap  and  the  main  cylinder  head  are  made  gas  tight  by 
lead-ring  gaskets  in  a  groove  into  which  a  projecting  ring  fits. 
These  rings  and  the  method  of  holding  the  head  are  made  clear 
in  the  picture.  The  set  screw  holding  down  the  valve  housing 
is  in  reality  a  safety  device,  for  should  scale  or  other  obstruction 
fall  on  top  of  the  piston  the  bolt  would  break  when  the  obstruc- 
tion was  brought  up  against  the  valve  housing  at  the  top  of  the 
stroke.  The  lower  discharge  valves  are  attached  to  housings 
at  the  bottom  of  the  cylinder.  The  stuffing-box  gland  is  shown 
in  the  figure  and  owing  to  the  peculiar  use  of  oil  in  this  cylinder 
there  is  no  provision  for  introducing  oil  into  the  gland. 

A  peculiar  feature  of  this  compressor  and  that  of  the  de  La 
Vergne  Company  is  the  introduction  of  a  spray  of  light  paraffine 
oil  on  each  stroke.  After  spraying  this  oil  forms  a  thin  layer 
over  the  top  of  the  piston  on  the  down-stroke  and  one  on  the 
lower  cylinder  head  on  the  up-stroke.  In  this  way  the  piston 
and  piston  rod  are  sealed  with  oil,  thus  cutting  down  the  tendency 
to  leak.  This  oil  also  fills  up  the  clearance  space  at  the  top  end 
of  the  stroke.  The  excess  oil  is  driven  out  through  the  valves. 
This  of  course  reduces  the  clearance  to  zero.  At  the  lower  end 
of  the  stroke  the  oil  would  not  flow  away  readily,  so  valves  are 
introduced  into  the  piston  allowing  oil  to  enter  the  hollow  part 


118 


ELEMENTS  OF  REFRIGERATION 


TYPES  OF  MACHINES  AND  APPARATUS          119 

of  the  piston.  From  this  space  the  oil  discharges  through  the 
upper  discharge  valve,  when  it  is  connected  with  this  space 
at  the  lower  end  of  the  stroke  by  an  opening  in  the  side  of 
the  piston.  In  this  way  the  oil  is  carried  out  without  the 
danger  of  breaking  the  compressor.  This  injection  of  liquid 
also  absorbs  some  of  the  heat  of  compression  and  makes  the 
work  less. 

The  piston  is  fairly  deep  considering  the  fact  that  the 
oil  seal  cuts  down  the  amount  of  leakage.  This  also  reduces 
the  friction.  The  piston  rod  is  held  to  the  piston  by  a  circular 
nut  and  projecting  collar.  The  construction  with  two  parts 
is  clearly  shown. 

The  false  cap  held  on  the  cylinder  head  by  the  tap  bolt  is 
for  finish  only. 

The  suction  and  discharge  pipes  are  attached  by  means  of 
flange  unions. 

The  use  of  oil  requires  additional  apparatus  to  recover  the 
oil  from  the  discharge.  The  heated  gas  is  first  passed  through 
the  fore  cooler,  Fig.  39,  and  after  being  cooled  it  is  taken  to  the 
pressure  tank,  where  the  oil  separates  out  and  the  remaining  gas 
goes  to  the  condenser.  The  oil  taken  out  goes  back  through 
the  strainer  to  the  engine;  other  oil  which  enters  the  condenser 
is  finally  separated  from  the  liquid  ammonia  in  the  separating 
tank.  The  oil  here  separates  and  passes  over  to  the  com- 
pressor, being  sucked  in  on  the  proper  stroke.  Fresh  oil  may 
be  added  to  the  system  by  the  oil  pump  when  needed. 

The  liquid  ammonia  is  taken  from  the  storage  and  separating 
tanks  by  the  main  liquid  line  to  the  various  expansion  coils  in 
rooms  or  brine  tank.  The  suction  is  brought  back  to  the  main 
suction  pipe  of  the  compressor. 

Fig.  40  illustrates  a  horizontal  type  of  compressor  brought 
out  by  this  company.  The  suction  valve  A  opens  into  the 
passage  B,  which  is  connected  to  the  cylinder  C.  The  suction 
valve  with  its  seat,  spring  and  dash  pot  are  in  a  housing  which 
is  held  in  place  by  a  bonnet  or  cover-plate.  The  discharge 
valve  D  is  in  a  similar  housing.  Either  of  the  valves  may  be 
examined  by  simply  removing  the  head.  The  housings  are 


t 

1 


TYPES  OF  MACHINES  AND  APPARATUS  121 

arranged  with  slots  so  that  gas  from  the  suction  main  E  enters 
the  space  F  and  goes  through  the  valve  from  this  into  the 
cylinder.  In  the  same  way  the  discharge  from  the  valve  D 
passes  through  G  into  the  discharge  main  H.  In  this  cylinder 
there  is  no  chance  for  the  valves  falling  into  the  cylinder  and 
any  scale  or  obstruction  would  tend  to  fall  into  the  space  at 
the  lowest  point  of  the  cylinder  barrel.  The  piston  and  its 
attachment'  to  the  rod  are  clearly  shown.  The  double-lanterned 
stuffing-box  is  shown.  This  is  due  to  the  fact  that  there  is 
no  oil  lying  around  the  rod  as  in  the  former  case.  The  lubrica- 
ting oil  enters  at  I  and  is  taken  out  at  /.  At  K  in  certain  cases, 
a  connection  is  made  to  the  suction  pipe  to  remove  any  ammonia 
which  has  leaked  past  the  first  set  of  packing  rings. 

The  cylinder  is  surrounded  by  the  jacket  M . 

The  cylinder  of  a  horizontal  double-acting  compressor  of 
the  Frick  Co.  is  shown  in  Fig.  41.  This  company  builds  ver- 
tical compressors  which  are  very  similar  in  general  features  to 
the  compressor  of  the  York  Manufacturing  Co.,  so  that  no  section 
of  that  type  will  be  shown.  The  cylinder  is  provided  with 
valves  in  the  spherical  heads  arranged  in  radial  lines.  They 
are  arranged  in  this  manner  to  increase  the  valve  area  for  a 
given  diameter  of  cylinder  while  using  a  small  amount  of  clear- 
ance. There  are  usually  two  suction  valves  and  two  discharge 
valves  on  each  end.  The  two  upper  valve  boxes  are  con- 
nected, as  are  the  two  lower  discharge  boxes.  As  shown 
in  the  figure,  these  valves  are  so  arranged  that  the  seats, 
springs  and  valves  may  be  removed  with  the  valve  housings 
by  simply  removing  the  bonnets.  The  long  stuffing-box,  the 
wide  piston,  the  packing  ring  for  the  lead  gasket  in  the  heads 
and  bonnets,  the  water  jacket  and  the  other  peculiar  features 
of  ammonia  compressors  are  clearly  seen.  The  piston  rod  is 
properly  attached  by  a  nut.  Some  builders  attach  the  rod  by 
peening  over  the  end  after  forcing  the  rod  on  the  piston.  This 
is  not  good  practice  and  should  not  be  resorted  to  unless  ab- 
solutely necessary.  It  is  better  to  use  some  form  of  nut  or 
cotter  pin.  The  piston  is  made  in  two  parts,  making  a  simple 
core  arrangement  in  casting.  To  stiffen  the  cylinder,  long 


E 


TYPES  OF  MACHINES  AND  APPARATUS 


123 


through  bolts  are  passed  from  one  end  to  the  other,  thus  relieving 
the  cylinder  of  strain.  The  stuffing-box  is  provided  for  an  oil- 
supply  attachment,  and  an  ammonia  pipe  returns  to  the  suction 
pipe  gases  which  leak  out;  these  features  are  shown  by  dotted 
circles  at  the  center  of  the  rods. 

For  the  proper  operation  of  compressors  it  is  necessary  at 
times  to  remove  the  vapor  from  the  cylinder.     To  do  this  there 


FIG.  42. — Frick  Manipulating  Valves  for  Small  Compressors. 

are  certain  by-pass  arrangements  common  to  most  compressors. 
The  arrangements  used  by  the  Frick  Company  are  shown  in 
Figs.  42  and  43.  To  exhaust  the  vapor  from  one  compressor 
the  machine  is  shut  down  and  all  of  the  valves  are  closed.  The 
purge  valve  10  is  opened.  This  permits  gas  to  escape.  The 
machine  is  now  operated  slowly.  The  cylinder  head  of  L  may 
be  removed.  To  exhaust  R,  the  same  method  is  used. 

To  exhaust  the  condenser  and  store  the  ammonia  in  the 
expansion  coils,  close  all  valves  after  shutting  down,  then  open 


124 


ELEMENTS  OF  REFRIGERATION 


the  valves  i,  2,  3,  4  and  12  and  start  the  machine  slowly.  The 
gas  for  compressors  is  sucked  through  valves  i,  12  and  2  from 
the  discharge  main,  while  after  compression  it  is  discharged 
through  3  and  4  into  the  suction  piping. 

To  admit  air  into  the  high  side  for  testing,  close  the  suction 
valves  5  and  6,  and  leave  the  discharge  valves  7  and  8  open. 
Open  valves  i  and  2,  removing  the  plug  from  tee  n.  Valves 
3,  4  and  12  are  closed.  Air.  is  then  drawn  in  by  i  and  2,  when 
the  compressor  is  driven  slowly. 

To  admit  air  for  testing  low  side,  the  suction  valves  5  and  6 
and  the  discharge  valves  7  and  8  are  closed.  Valves  i,  2,  3,  4 


U  5 


FIG.  43. — Frick  Manipulating  Valves  for  Large  Compressors. 


are  opened  and  the  plug  in  tee  n  is  removed. T  Air  will  enter  i 
and  2  when  the  compressor  is  run  slowly  and  the  discharge  is 
passed  into  the  suction  main  by  3  and  4. 

Before  air  is  introduced  on  either  side  the  ammonia  is  ex- 
hausted from  that  side  by  pumping  the  ammonia  into  the  other 
until  a  low  vacuum  exists  on  the  side  from  which  the  vapor  is 
being  pumped. 

For  larger  compressors  a  different  arrangement  of  pipes  is 
used,  as  shown  in  Fig.  43.  In  this  case,  valves  i  and  2  are 
attached  to  valves  5  and  6  and  then  valves  9  and  10  are  added 
to  the  pipes  running  from  4  to  i  and  from  3  to  2,  while  valve 
1 1  connects  to  the  suction  pipe. 


TYPES  OF  MACHINES  AND  APPARATUS 


125 


To  exhaust  the  compressor  R,  all  valves  are  closed  after 
shutting  down  the  compressor.  Then  stop  valve  8  is  opened 
with  2  and  3.  The  valve  10  when  closed  prevents  any  con- 
nection to  the  suction  at  that  point.  If  the  compressor  is 
started  slowly,  the  compressor  L  draws  from  R  and  frees  it  of 
ammonia.  Valve  2  opens  inside  of  6. 

To  exhaust  the  condenser  the  valves  opened  are  8,  i,  4,  3, 
10  and  ii.  In  this  case  the  gas  is  sucked  from  the  discharge 
pipe  through  8,  4,  and  i  into  R  and  then  the  compressor  vapor 
passes  over  through  3,  10  and  n  into  the  suction  mains.  The 


FIG.  44. — Section  of  Arctic  Horizontal  Double  Single-acting  Compressor. 

other  compressor  could  have  been  used.  To  empty  the  suction 
the  compressor  is  operated  in  the  usual  way  with  the  reducing 
pressure  valve  closed. 

One  recent  improvement  in  the  arrangement  of  compressors 
is  that  of  the  Arctic  Machine  Co.  in  their  center  inlet  horizontal 
double-acting  compressor  shown  in  Figs.  44  and  45.  In  this 
compressor  the  inlet  valves  in  the  piston  are  similar  to  the 
hurricane  inlet  valves  of  the  Ingersoll-Rand  air  compressors. 
To  avoid  the  piston-rod  inlet  connection,  the  two  piston  faces 
are  separated  a  distance  equal  to  the  stroke  of  the  compressor 
and  the  center  of  the  piston  barrel  is  cast  with  openings  leading 


126 


ELEMENTS  OF  REFRIGERATION 


from  a  ring  passage  into  the  cylinder  bore.  The  suction  vapor 
enters  this  passage  and  the  space  between  the  two  piston  faces. 
There  are  a  series  of  openings  extending  through  the  piston 
face  near  the  periphery  and  these  are -covered  by  a  ring  of 
metal.  When  the  piston  starts  from  one  end,  a  vacuum 
forms  behind  the  piston,  and  the  gas  between  the  piston  faces, 
being  at  a  higher  pressure,  forces  the  ring  out  against  a  stop 
and  enters  behind  the  piston  with  little  change  in  pressure. 
At  the  other  end  of  the  stroke,  the  acceleration  of  the  recipro- 
cating parts  when  the  piston  begins  the  return  stroke  closes 
this  valve  and  the  piston  begins  to  compress.  In  this  way 


falve  Open  Valve  Closed 

FIG.  45. — Suction  Valves  and  Pistons  of  Arctic  Compressor. 

the  compressor  acts  rapidly  on  the  suction  stroke  with  little 
drop  in  pressure. 

The  discharge  valves  and  housing  are  connected  to  the 
lowest  part  of  the  cylinder  at  each  end,  thus  caring  for  scale 
and  liquid.  These  valves  may  be  examined  by  removing  the 
bonnet.  The  springs  and  dash  pot  are  seen  in  the  figure. 

The  cold  ammonia  coming  to  the  center  does  not  affect  the 
stuffing-boxes  and  the  jackets  are  removed  from  the  cold  parts 
of  the  cylinder.  An  insulating  filling  is  placed  at  the  center  to 
cut  down  radiation.  The  heads  are  jacketed  as  well  as  the  barrel 
ends.  The  path  of  the  water  is  seen. 

The  stuffing-box  is  shown  with  its  oil  connections.  There 
is  also  a  connection  leading  from  the  stuffing-box  to  the  suction 
main. 

The  piston  detail  is  shown  in  Fig.  45.     The  valve  disc  is 


TYPES  OF  MACHINES  AND  APPARATUS 


127 


the  ring  A ,  the  motion  of  which  is  limited  by  the  guard  ring 
or  projection  B.  The  openings  C  are  distributed  around  the 
periphery  of  the  piston.  The  method  of  attaching  the  piston 
is  proper  in  this  case  as  the  load  is  taken  by  a  shoulder. 
Each  of  the  piston  faces  is  in  reality  a  single-acting  compressor. 
The  action  of  the  suction  valve  is  so  free  that,  according  to 
reports  on  the  compressor,  the  suction  drop  was  only  i  Ib.  at 
300  R.P.M. 

The  valves  of  the  compressor  of  the  Triumph  Ice  Machine 


FIG.  46. — Valves  of  the  Triumph  Ice  Machine  Co.  Compressor. 


Co.  are  shown  in  Fig.  46.  These  valves  and  their  seats  are 
held  in  a  housing  or  cage  which  is  held  in  place  by  a  nut  screwed 
into  the  valve  cavity  and  containing  set  screws  to  hold  the  cage 
tight  against  the  head  casting.  The  suction  valve  spindle  is 
held  up  by  two  springs  each  with  a  separate  adjusting  collar. 
These  collars  may  be  held  tight  by  jamb  nuts  or  set  screws. 
The  small  collar  at  the  lower  end  of  the  suction  spindle  acts 
as  a  dash  pot. 

In  the  discharge  valve  there  are  two  springs  holding  the 
valve  down  and   a  cup  acting  on  a  shoulder  or  collar  on  the 


128 


ELEMENTS  OF  REFRIGERATION 


TYPES  OF  MACHINES  AND  APPARATUS  129 

spindle  serves  as  a  piston  and  dash  pot.  In  each  case  the 
long  spindle  guide  keeps  the  valves  in  line. 

The  cylinder  of  a  carbonic  acid  machine  will  be  shown 
because  of  the  special  features  due  to  the  high  pressures  carried. 
One  of  the  best  known  compressors  of  this  type  is  that  of 
Kroeschell  &  Co.  and  is  shown  in  Fig.  47.  The  cylinder  is  a 
rectangular  steel  forging  in  which  the  ports  are  drilled  from  one 
end.  The  various  valves  are  placed  in  housings  which  are  held 
in  place  by  bonnets.  These  valves  are  operated  by  springs 
as  shown.  The  suction  valves  have  helical  springs  while  a  cap 
on  the  top  of  the  spindle  limits  its  movement.  The  discharge 
valves  have  a  spring  to  support  them  and  a  flat  spiral  spring 
to  force  them  back.  The  seats  are  held  in  by  bonnets  or  cages 
and  may  be  removed  readily.  The  bonnets  are  made  tight  by 
fiber  washers. 

The  piston  is  packed  with  cup  leathers  to  sustain  the  high 
pressure.  One  end  is  flat  because  of  the  head  and  the  other  end 
is  spherical  in  order  to  place  the  two  suction  valves  and  one 
discharge  valve. 

The  piston  rod  is  packed  with  a  series  of  cup  leathers  with 
provision  for  circulating  oil. 

The  two  suction  passages  are  connected  around  the  head 
valve,  the  suction  pipe  entering  one  of  the  passages  at  the  center 
as  shown.  The  discharge  passage  is  connected  to  the  top  face 
of  the  cylinder.  Each  of  these  is  controlled  by  a  valve.  The 
valves,  Fig.  47,  have  drips  or  scale  chambers  at  the  bottom  to 
catch  dirt.  The  discharge  passage  is  connected  to  an  open- 
ing covered  by  a  thin  plate  which  will  break  when  excessive 
pressure  is  brought  on  the  discharge  by  shutting  off  the 
discharge  stop  valve  or  by  a  stoppage  of  the  system.  A 
relief  valve  is  also  fixed  on  the  suction  side  to  relieve  excess 
pressure. 

The  parts  of  this  compressor  are  made  of  steel,  due  to  the 
heavy  pressures.  The  remaining  part  of  the  compressor  is 
similar  to  any  other  type. 

Fig.  48  shows  one  of  the  Kroeschell  marine  compressors  in 
which  the  double-pipe  brine  cooler  and  double-pipe  condenser 


130 


ELEMENTS  OF  REFRIGERATION 


TYPES  OF  MACHINES  AND  APPARATUS          .     131 

are  placed  in  the  base  of  steel.     The  steam  engine  driving  this 
is  seen  at  one  side  of  the  compressor. 

One  of  the  latest  types  of  machines  in  which  the  compressor, 
condenser,  brine  cooler,  and  pipe  system  are  contained  within 
the  same  casing  is  shown  in  Figs.  49  and  50.  This  is  the 
Audiffren-Singrun  Refrigerating  Machine.,  as  sold  by  the  H.  W. 
Johns-Manville  Co.  In  the  spherical  case  A  is  a  hollow  shaft 
B,  supporting  as  an  axis  a  casting  V  which  is  so  heavily  weighted 
by  W  that  it  will  not  turn.  This  casting  carries  the  trunnions 
TT  of  a  cylinder  C,  the  piston  of  which  is  connected  to  a  rod 
attached  to  the  strap  of  an  eccentric  sleeve  D  on  the  shaft. 
If  the  whole  casing  is  turned  and  with  it  the  shaft,  the  heavy 
weight  remains  down  and  the  piston  in  the  cylinder  is  drawn 
in  and  out  by  the  eccentric  while  the  cylinder  oscillates.  Thus 
oscillation  of  the  cylinder  between  the  faces  of  the  suspended 
casting  causes  the  face  of  the  cylinder  casting  to  oscillate  over 
the  face  of  the  right-hand  casting  which  contains  holes.  In  this 
way  the  ports  of  the  two  ends  of  the  cylinder  are  connected  to 
suction  ports  N  in  the  hanging  casting  at  the  proper  time  in  the 
same  way  as  the  distribution  of  steam  is  accomplished  in  the 
oscillating  engine.  In  this  way  862  vapor  is  admitted  to  the 
cylinder  from  the  annular  space  E  between  the  two  shafts  and  the 
space  F  when  the  holes  at  G  in  the  cylinder  and  face  come  oppo- 
site. The  vapor  is  compressed  in  the  cylinder  and  when  the 
proper  pressure  is  reached  the  discharge  valves  at  H  open  and  dis- 
charge the  vapor  into  the  casing  A .  The  casing  revolves  in  a  tank 
7,  Fig.  50,  containing  the  cooling  water.  This  condenses  the 
sulphur  dioxide  and  the  liquid  collects  at  the  outer  part  of  the 
casing  A ,  and  is  caught  up  by  a  scoop  M,  and  is  conducted  to  the 
reservoir  /.  It  is  then  delivered  to  a  regulating  float  throttle 
valve  after  the  lubricating  oil  is  removed  from  the  862.  The 
oil  flows  over  at  U  into  the  chamber  O  in  which  the  cylinder 
is  placed.  Thus  the  eccentric  and  cylinder  are  flooded  with 
oil.  This  whole  region  is  under  pressure,  so  that  there  is  no 
leakage  from  the  compressor.  There  is  a  tendency  for  the  oil 
to  enter  around  the  piston  rod  and  between  the  valve  faces- 
The  spring  X  holds  the  system  against  the  sliding  face.  The 


132 


ELEMENTS  OF  REFRIGERATION 


i 


TYPES  OF  MACHINES  AND  APPARATUS 


133 


liquid  S02  at  low  pressure  after  passing  the  throttle  valve  travels 
along  the  inner  pipe  extending  between  the  two  vessels  and  finally 
settles  to  the  circumference  of  the  other  spherical  vessel,  due  to 
centrifugal  force,  and  it  is  evaporated  as  it  removes  heat  from 
the  brine  in  the  tank  R,  Fig.  50.  The  vapor  is  returned  through 
a  space  formed  between  the  two  pipes  between  A  and  (/,  and 
passes  into  the  SCb  compressor.  The  complete  system  is  con- 
tained within  a  tight  set  of  vessels  and  pipes,  and  there  are  no 
moving  joints  to  be  kept  tight.  There  is  no  danger  of 
leakage.  An  extension  on  the  right-hand  vessel  serves  as 
one  journal  for  the  system  and  the  intermediate  pipe  serves 


FIG.  50. — Audiffren  Singrun  Apparatus. 

as  the  other.  There  is  little  weight  on  the  journals,  as  the 
buoyancy  from  the  immersed  vessels  supports  much  of  the 
weight.  The  gas  pressure  in  A  tends  to  hold  the  oscillating 
piston  against  its  face  in  addition  to  the  spring  pressure, 
and  keeps  the  sliding  joint  tight.  Should  the  condensing 
water  be  shut  off  and  the  temperature  rise,  the  high  pressure 
developed  Vould  finally  be  sufficient  to  cause  the  weight  to 
rotate  and  so  prevent  a  further  rise  in  pressure.  The  small 
valve  at  5  is  held  down,  when  the  apparatus  is  in  opera- 
tion, by  centrifugal  force,  but  upon  stopping  the  machine  this 
valve  is  opened  by  the  weight  of  the  balls,  thus  equalizing 
the  pressure.  The  following  table  gives  the  data  for  these 
machines: 


134 


ELEMENTS  OF  REFEIGERATION 


Capacity  in  Tons. 

Size  of 
Machine. 

Power  Required. 

R.P.M. 

Refrigeration. 

Ice. 

2 

O.IQ 

0.13 

0.4  to  0.6  H.P. 

380 

3 

0.48 

o;32 

i  to  i  .  5 

280 

4 

o.q6         i         0.66 

2   tO   2.25 

190 

6 

I.Q2 

1.32 

4  to  4  .  50 

140 

The  great  advantage  of  such  a  machine  lies  in  the  fact  that 
there  is  no  manipulation  of  valves,  stuffing-boxes,  gauges  or 
oiling  devices. 

In  Fig.  50  the  general  arrangement  of  this  apparatus  is  seen. 
The  cooling  water  in  7  liquefies  the  SO2,  while  the  evaporation 
of  the  SC>2  cools  the  brine  in  the  tank  R.  If  this  brine  is  cooled 
completely  there  will  be  no  evaporation  of  S02,  and  there  will 
be  no  gas  sent  back  to  the  compressor,  and  consequently  none 
will  be  liquefied  in  the  case  in  A .  Hence,  after  a  short  time  the 
level  of  the  liquid  in  /  will  be  such  that  the  float  valve  K  will 
be  closed  off  and  no  more  liquid  862  can  pass  over  to  R.  The 
motor  is  attached  to  the  pulley  Z. 

The  above  gives  the  necessary  details  of  the  compression 
machines.  The  parts  of  the  absorption  machine  will  now  be 
considered. 

Generators.  In  Fig.  19  a  cross-section  through  a  generator 
is  shown.  This  is  seen  to  be  made  of  a  circular  tank  with 
flanged  ends  and  dished  heads,  containing  several  coils  of  steam 
pipes  connected  to  manifolds.  This  is  of  cast  iron,  and  bolted 
to  a  T-connection  is  the  analyzer,  containing  a  series  of  trays 
over  which  the  liquor  from  the  exchanger  and  rectifier  flows. 
The  pipes  are  so  arranged  that  the  gases  have  to  pass  through 
the  liquid.  The  cast  head,  dished  to  give  strength,  is  shown. 

In  Fig.  51,  the  generator  of  the  Henry  Vogt  Company  is 
shown.  In  this  strong  liquor  flows  into  the  top  section  of  the 
generator  from  the  exchanger.  The  excess  liquor  flows  from  this 
at  the  left-hand  end  to  the  next  section,  and  the  excess  from 
this  might  flow  into  a  lower  section  if  used.  In  this  way  the 
liquor  travels  the  whole  length  of  the  section  before  leaving  it. 


TYPES  OF  MACHINES  AND  APPARATUS 


135 


The  weak  liquor  is  taken  off  at  the  right-hand  end  of  the 
lower  section.  The  connections  are  made  to  give  a  definite 
liquid  level  in  each  section.  The  vapor  formed  in  each  section 
is  taken  up  through  a  main  pipe  to  the  rectifier.  The  steam 
coils  are  connected  to  manifolds  which  are  connected  together 


FIG.  51.— Vogt  Double  Cylinder  Generator. 


FIG.  52. — Vogt  Modern  Generator. 

on  the  steam  side  and  at  "the  discharger  end.  The  cylinders 
and  heads  are  made  of  cast  iron  and  the  supports  are  made  to 
carry  these  from  the  lower  sections. 

The  analyzer  is  arranged  at  times  to  cause  the  vapors  to 
travel  up  through  the  strong  liquor  which  flows  over  per- 
forated plates.  The  gas  is  then  carried  to  the  rectifier. 

Fig.  52  is  a  section  of  one  of  the  later  forms  of  Vogt  gen- 


136 


ELEMENTS  OF  REFRIGERATION 


erator.  The  generator  is  made  of  semi  steel  pipe  with  dished 
heads  using  a  tongue  and  groove  packing.  The  strong  liquor 
pipe  passes  through  a  stuffing  box  and  is  attached  to  the 
analyzer  header  A.  From  this  point  the  liquor  is  carried  into 
a  number  of  tubes  forming  the  analyzer  in  this  case.  These 
are  in  the  space  through  which  the  heated  gases  pass  on  the 
way  to  the  outlet  and  dry  pipe  B. 

The  weak  liquor  is  taken  from  C  and  at  DD  the  glass  gauge 
gives  the  level  of  the  liquor.  The  evaporation  occurs  at  the 
surface  of  the  closed  steam  pipes,  E,  which  are  screwed  into 
the  head.  The  manifold  cap  has  a  series  of  small  tubes,  G, 


Liquor 


Vapor 


FIG.  53.— Vogt  Rectifier. 


attached  to  it,  and  taking  steam  from  F  to  the  ends  of  the 
closed  tubes.  Then  the  condensed  steam  is  removed  at  the 
lower  part  of  the  head. 

This  construction  is  quite  simple  and  effective. 

Rectifier.  The  rectifier  is  made  in  several  ways.  In  some 
cases,  as  in  Fig.  19,  it  consists  of  a  coil  of  pipe  made  up  of  return 
bends,  through  which  the  vapors  flow  to  the  separator  and  con- 
denser while  cooling  water  is  passed  over  it.  In  other  cases  it 
is  formed  as  a  double-pipe  condenser,  the  construction  of  which 
will  be  explained  later.  When  this  double-pipe  apparatus  is 
used,  Vogt  uses  the  strong  liquor  as  cooling  substance,  passing 
it  directly  to  the  rectifier  before  it  enters  the  exchanger. 


TYPES  OF  MACHINES  AND  APPARATUS 


137 


Exchanger.  The  exchangers  are  of  various  forms.  In  Fig. 
19  the  form  is  a  cast-iron  cylinder  with  a  coil  within.  This 
coil  carries  the  weak  liquor  and  while  the  strong  liquor  passes 
around  this  coil  as  it  goes  through  the  shell.  The  York  Com- 
pany and  Vogt  use  a  double  pipe  construction  for  this  apparatus. 

Weak  Liquor  Cooler.     This  is  of  double-pipe  construction. 

Absorber.  The  absorber  is  made  in  several  forms.  In  all  of 
them  vapor  enters  at  bottom  and  is  distributed  through  a  per- 
forated pipe.  The  weak  liquor  is  distributed  near  the  top  of 
the  absorber,  the  flow  of  weak  liquor  being  controlled  by  a 


Weak  LiquidJnlet 


FIG.  54. — Vogt  Absorber. 

float  shown  in  Fig.  55.  This  float  is  attached  to  the  side  of  the 
a  sorber.  The  action  of  the  float  is  to  control  the  admission  of 
weak  liquor  by  the  valve  A.  The  strong  liquor  is  pumped 
from  the  bottom  of  the  vessel,  which  is  usually  made  cylindrical. 
In  the  absorber  there  are  sets  of  tubes  carrying  cold  water  to 
remove  the  heat  of  absorption. 

Fig.  19  gives  the  construction  used  by  the  Carbondale  Co., 
while  Fig.  54  is  the  absorber  of  Henry  Vogt  &  Co.  The  drawing 
shows  the  construction  and  the  manner  in  which  there  are  four 
passes  of  the  water. 

The  other  parts  of  the  apparatus  being  used  with  this  and 
compression  machines  will  now  be  described. 


138 


ELEMENTS  OF  REFRIGERATION 


Piping.     The  piping  for  ammonia  should  be  full  weight  or 
extra   heavy   wrought-iron    pipe.      The    pipe   is   united   with 


FIG.  55. — Vogt  Regulator  for  Weak  Liquor  Inlet. 

screwed  fittings,  flanged  fittings  and  by  welding.  For  use  with 
CO2  extra  heavy  pipe  must  be  used.  This  is  determined  by 
the  pressure  to  be  carried  and  the  opinion  of  the  engineer. 


TYPES  OF  MACHINES  AND  APPARATUS      139' 

Ammonia  pressures  will  run  as  high  as  200  Ibs.  per  sq.in.,  while 
carbon  dioxide  may  be  1000  to  1200  Ibs.  The  best  method  of 
uniting  these  pipes  is  by  welding,  as  there  is  no  chance  for 
leakage,  although  they  cannot  be  dismantled  easily.  Weld- 
ing is  done  by  the  use  of  thermit,  the  oxy-acetylene  torch  or  by 
electricity.  In  this  work  the  parts  are  clamped  together  tightly 
and  thermit  is  ignited  in  a  crucible,  after  which  the  aluminum 
oxide  and  the  hot  iron  are  poured  into  a  mold  around  the  pipe 
and  produce  a  welding  temperature.  Thermit  is  a  mixture  of 
Fe20a  and  2A1.  It  burns  to  2Fe  and  A^Oa,  producing  a  tem- 
perature so  high  that  the  molten  iron  and  slag  can  heat  the 
pipe  to  a  proper  point  for  welding.  The  thermit  powder  is  held 


FIG.  56. — Thermit  Pipe  Welding. 

in  a  crucible  and  after  ignition  is  complete  it  is  poured  into 
the  mold  around  the  part  to  be  welded. 

Before  welding  the  pipe  ends  are  milled  smooth  by  a  special 
facing  machine  and  are  then  clamped  and  held  tightly  together. 
An  iron  mold  is  then  put  around  the  pipe  and  the  thermit 
poured  in  as  shown  in  Fig.  56.  When  the  operator  feels  the 
clamp,  Fig.  57,  yield  he  knows  that  the  iron  has  reached  a  weld- 
ing heat,  and  by  pulling  the  clamps  together  and  giving  four 
quarter  turns  of  the  bolt  the  weld  is  made.  After  the  weld  is 
made  the  mold  should  be  left  ten  or  fifteen  minutes  if  possible, 
and  then  removed.  The  iron  and  slag  will  fall  away.  Thermit 
is  placed  in  bags  with  the  proper  amount  for  a  given  size  pipe. 
In  igniting  it,  it  is  customary  to  use  about  one-half  of  the  package 
at  first  and  then,  after  igniting  it  by  means  of  an  ignition  powder 
and  Hatch,  the  remainder  of  the  package  is  poured  in.  The 


140  ELEMENTS   OF  REFRIGERATION 

slag  first  forms  a  coating  around  the  pipe,  protecting  it  from 
the  molten  iron.  The  heat  is  used  only  to  bring  the  iron  to 
a  welding  temperature. 

Tests  of  pipes  welded  in  this  manner  have  shown  that  the 
weld  is  as  good  as  the  pipe  in  tension,  torsion  and  bending  tests. 
The  cost  of  thermit  welding  amounts  to  75%  of  the  cost  of 
elbows  or  flanged  joints  for  small  sizes,  while  for  four-inch  flanged 
joints  the  thermit  cost  is  greater  than  the  cost  of  fittings. 

The  use  of  the  oxy-acetylene  torch  is  valuable  in  cutting 
as  well  as  in  welding.  C2H2  is  mixed  with  Cb  in  the  nozzle, 
and  if  just  enough  oxygen  is  introduced,  the  flame  will  consist 
of  CO2  and  H2O.  The  heat  is  produced  by  the  breaking  down 
of  the  C2H2  and  by  the  formation  of  CCb  and  H20.  An 


(  FIG.  57.— Thermit  Welding  Clamp  and  Mold. 

intense  flame  temperature  is  obtained.  When  welding  is  de- 
sired the  mixture  is  as  given  above,  and  by  pressing  the  parts 
together  and  melting  a  stick  of  steel  by  the  flame  to  flow  into 
the  interstices  a  fixed  weld  is  made.  If  it  is  desired  to  cut  the 
metal,  a  correct  burning  mixture  is  used  on  the  outer  part  of 
the  flame  and  after  this  heats  the  metal,  a  flame  rich  in  oxygen 
is  thrown  out  from  the  center  of  the  nozzle  and  burns  a  groove 
through  the  metal.  This  torch  is  particularly  valuable  for 
welding  plate,  work.  The  temperature  is  so  high  that  the  H2O 
is  dissociated  and  the  hydrogen  burns  on  the  outside  of  the 
flame. 

In  electric  welding;  an  alternating  current  of  low  voltage 
but  great  current  strength  is  delivered  from  a  transformer 
through  large  leads  clamped  to  the  pipes  to  be  welded.  The 


TYPES  OF  MACHINES  AND  APPARATUS 


141 


142 


ELEMENTS  OF  REFRIGERATION 


resistance  at  the  butted  ends  to  be  welded  soon  causes  these  to 
become  white  hot  and  the  metal  is  welded. 

The  fittings  on  pipes  are  usually  screwed  on.  The  taper 
thread  is~carefully  cut  and  the  joint  made  tight  by  a  mixture 
of  litharge  and  glycerine.  This  forms  a  cement  and  makes  a 
good  joint  if  the  fittings  are  made  tight.  At  times,  with  black 
iron,  the  threads  are  tinned  over,  when  the  solder  makes  a 
joint  if  they  are  screwed  together  when  hot.  This  method 
should  not  be  used  with  galvanized  pipe.  There  are  claims  for 
each  method. 

The  flanged  unions,  Fig.  58,  are  used  for  uniting  sections 


FIG.  59. — Boyle  Union. 

which  may  have  to  be  separated.  They  are  screwed  to  the  pipe 
as  shown  in  the  figure  or  sometimes  the  type  shown  at  C  is 
used.  B  shows  the  flange  joint  of  the  de  La  Vergne  Co.  It 
has  a  cavity  left  at  the  upper  end  of  the  screwed  portion  of  the 
flange  into  which  solder  may  be  left  as  it  is  forced  out  from 
the  tinned  threads  when  the  flange  and  pipe  are  heated  and 
forced  together.  This  fills  the  space  and  threads  at  one  end 
with  solder  so  as  to  make  a  solid  gas-tight  joint.  The  flanges 
are  made  of  a  close-grained  malleable  iron  combining  strength 
and  toughness,  or  else  drop  forgings  or  steel  castings  are 
employed. 

The  joint  between  the  two  flanges  is  made  tight  by  a  lead 
gasket  which  fits  in  a  groove  in  one  flange  and  is  pressed  down 


TYPES  OF  MACHINES  AND  APPARATUS 


143 


by  a  projecting  ring  on  the  other  flange.     At  times  lead  gaskets 
are  placed  between  flanges  as  shown  in  A   and  C.     Fig.   59 


FIG.  60.— Elbows. 

illustrates  a  Boyle  union  used  in  refrigerating  work.     In  this 
a  change  of  alignment  is  possible  by  properly  finishing  the  ends 

of  the  nipple. 

Where  elbows  are  needed  they 
may  be  screwed  as  shown  in  Fig. 
60  B,  and  sometimes  it  may  be 
necessary  to  use  a  flanged  elbow, 
the  flange  being  on  one  outlet  as 
in  the  figure.  Very  often  both  ends 
of  the  elbow  have  flanges.  A  tee, 
Fig.  6 1,  is  used  when  it  is  desired 
to  take  off  a  side  branch.  Return  bends  are  made  as  shown 


:   ! 

f-J 


FIG.  6 1. —Tee. 


144 


ELEMENTS   OF  REFRIGERATION 


TYPES  OF  MACHINES  AND  APPARATUS 


145 


in  Fig.  62.  These  tees  and  bends  show  different  arrangements 
used  in  ammonia  work.  Thus  one  bend  B  has  an  extra  flanged 
outlet  on  it.  It  is  a  special  return  bend  used  on  the  de  La 
Vergne  condensers  to  carry  off  condensed  ammonia.  If  it  is 
desired  to  connect  two  sections  of  a  coil,  two  flange  fittings 


FIG.  63. — Flanged  Return  Bend. 


W1WPF 

FIG.  64.— Branch  Tee  or  Manifold. 

known  as  return  bend  flanges  are  employed.     This  is  shown 
in  Fig.  63. 

Manifolds,  or  headers,  for  the  connections  of  a  number  of 
branches,  are  made  by  welding.  They  may  take  a  number  of 
special  forms,  depending  on  the  peculiarity  of  design.  Fig.  64 
illustrates  one  with  fifteen  branches  for  the  connection  of  the 


146 


ELEMENTS   OF  REFRIGERATION 


different  coils  of  a  condenser.  A  cross,  Fig.  65,  is  used  at  times 
when  two  lines  are  to  intersect  or  three  branches  are  to  be  taken 
from  a  line. 

All  of  the  fittings  are  extra  heavy  to  allow  for  the  high 
pressures,  and  after  erection  the  whole  system  is  filled  with 
air  under  pressure.  After  closing  the  valves  of  the  compressor 
the  system  should  hold  its  pressure  for  hours.  Leaks  may  be 
found  by  coating  over  the  pipes  and  fittings  with  soapy  water. 
In  the  shop  welded  joints  are  tested  by  immersing  the  apparatus 
in  a  tank  of  water  after  charging  it  with  air  under  pressure. 

Since  the  compression  heats  the  air  and  the  oil  vapor  from 


A 


\ 


•s: 


FIG.  65. — Cross. 


the  pipe  work  might  form  an  explosive  mixture  which  would 
ignite  at  the  temperature  due  to  compression,  Block  advises 
stopping  the  compressor  for  a  while  after  reaching  50,  100, 
150,  200,  and  250  Ibs.,  giving  the  air  some  time  to  cool. 

The  pipe  hangers  for  this  work  must  be  strong  and  well 
supported,  as  many  pipes  are  filled  with  brine  and  loaded  on  the 
outside  with  ice  and  snow.  The  weight  of  these  must  be  added 
to  the  weight  of  pipe  in  figuring  the  strength  of  the  hangers. 
Fig.  66  illustrates  several  methods  of  supporting  the  pipe. 

The  valves  used  as  stop  valves  on  the  vapor  line  are  of  various 
forms  with  strong  flanges  and  stuffing-boxes.  Usually  the  seat 
has  a  soft  lead  ring  for  giving  a  tight  joint,  and  the  stuffing-box 
is  long.  The  bonnet  of  the  valve  is  bolted  on  the  main  body, 


TYPES   OF  MACHINES  AND  APPARATUS  147 


© 


o 


I 


148 


ELEMENTS  OF  REFRIGERATION 


f 


TYPES  OF  MACHINES  AND  APPARATUS 


149 


using  a  lead  gasket.  Two  valves  are  shown  in  Fig.  67  and  each 
of  them  is  provided  with  flange  connections.  For  angle  con- 
nections, valves  are  built  in  this  form,  using  an  angle  body. 
Where  liquid  ammonia  or  vapor  is  to  be  prevented  from  return- 
ing, check  valves  are  used.  These  are  made  as  shown  in  Fig. 
68,  of  a  lift  type  known  as  the  cup  pattern,  due  to  the  guide 
cylinder  on  the  back,  or  they  may  be  of  the  swing  pattern. 
The  massive  construction  is  shown  here.  For  expansion  valves 
a  small  opening  which  may  easily  be  adjusted  for  small  changes 
is  used.  This  means  a  needle  valve  and  hence  the  forms  shown 
in  Fig.  69  are  employed.  In  each  of  these  the  needle  valve  is 


rrn 


FIG.  68.— Check  Valve. 

raised  by  a  fine-pitch  thread  so  as  to  give  close  regulation  on 
the  amount  of  liquid  discharged.  Safety  stop  valves  are  built 
for  the  discharge  valves  of  compressors.  These  valves  are  pro- 
vided with  a  spring-closed  by-pass  valve  which  only  opens  when 
the  pressure  reaches  a  high  value. 

Condensers.  The  ammonia  condensers  are  of  various  forms, 
depending  on  the  plant,  its  location  and  size.  An  open-air 
surface  condenser  should  be  used  when  the  cooling  water  carries 
scale-forming  salts  which  would  be  deposited  at  100°  F.  This 
condenser  may  be  of  several  forms.  If  welded  into  a  continuous 
coil  there  would  be  a  difficulty  in  renewing  a  part  of  it.  Fig.  70 
shows  the  welded  form  of  Kroeschell  &  Co.  for  C02-  Welded 
coils  are  rarely  used  as  condensers.  This  form  is  very  often 


150 


ELEMENTS  OF  REFRIGERATION 


used  as  an  expansion  coil.  In  Fig.  71,  a  condenser  fitted  with 
flange  joints  between  the  return  bends  and  pipes  is  shown, 
while  in  Fig.  72  screwed  joints  are  used.  In  Fig.  71  the 


I 

X 


o 
£ 


hot  ammonia  vapor  passes  through  two  lower  pipes  and  then 
is  taken  to  the  top  pipe  in  contact  with  the  coolest  water. 
This  water  is  distributed  from  the  perforated  or  split  pipe 
at  the  top  of  the  rack  of  tubes.  In  this  arrangement  there 


TYPES  OF  MACHINES  AND  APPARATUS 


151 


152 


ELEMENTS   OF  REFRIGERATION 


is  a  slight  counter-current  effect,  but  the  main  condenser  is  of 
parallel  flow.  In  Fig.  72  the  same  general  arrangement  has 
been  used  with  a  change.  After  the  liquid  is  formed  in  the 
condenser,  it  is  passed  through  a  small  pipe  contained  in  a  larger 
pipe,  and  through  the  annular  space  formed  between  the  two 
pipes  the  coldest  condensing  water  is  passed  on  its  way  to  the 
sprinkling  pipe.  In  this  way  the  liquid  is  cooled  to  almost  the 
lowest  temperature  of  the  cooling  water.  The  condenser  shown 
in  Fig.  73  is  one  in  which  vapor  enters  at  A ,  which  is  cooled  by 


Purge  Valve  ft 


Water  Enters 

TT 


->•  Saturated  Vapor 


FIG.  71. — Ammonia  Condenser  with  Flange  Joints. 

the  warmest  liquid,  and  any  condensation  which  occurs  is  taken 
off  at  B,  C  and  D,  and  is  passed  to  the  storage  tank.  Other 
liquid  is  taken  off  at  E.  The  cooling  water  enters  at  F  and  flows 
over  the  slot  in  the  top  of  the  distributing  pipe  and  falls  over  the 
pipes.  At  times  plates  are  placed  between  successive  pipes  so 
that  water  will  follow  from  pipe  to  plate  to  pipe  and  will  not 
be  blown  off  by  a  light  wind.  Flanged  joints  between  elbows 
forming  together  a  return  bend  permit  an  easy  method  of  con- 
struction. The  drips  at  certain  return  bends  are  cast  in  the 
bend.  The  connections  between  the  pipes  and  fittings  are 
screwed  joints. 


TYPES  OF  MACHINES  AND  APPARATUS 


153 


154 


ELEMENTS   OF   REFRIGERATION 


Of  course,  all  of  these  condensers,  known  as  atmospheric 
condensers,  have  the  water  sprinkled  over  the  surface  so  that 
when  the  wind  blows  the  water  may  be  blown  away  from  the 
pipe  surface  and  the  condensers  are  therefore  placed  in  shallow 
tanks  so  that  the  water  may  be  caught.  It  is  quite  customary 
to  shield  them  from  the  direct  action  of  the  wind  by  the  use  of 


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FIG.  73. — Sectional  Diagram  of  De  La  Vergne  Condenser. 

slatted  blinds.  By  inclining  these  properly  the  water  striking 
them  will  be  sent  back  to  the  tank. 

The  condensers  utilize  the  cooling  action  of  cool  air  blowing 
against  them  and  hence  in  cold  weather  the  supply  of  water 
is  decreased. 

In  small  plants  or  in  places  where  there  would  be  trouble 
from  the  falling  water,  a  submerged  condenser,  Fig.  74,  is  used. 
In  this  the  vapor  is  admitted  at  the  top  and  flows  downward. 
Cooling  water  enters  at  the  bottom  of  the  tank  and  flows  to  the 


TYPES  OF  MACHINES  AND  APPARATUS 


155 


sewer  from  the  top.  A  drain  placed  at  the  bottom  will  remove 
all  water  when  necessary  to  break  off  the  scale.  This  is  of  the 
counter-flow  type. 

One  of  the  best  forms  of  condenser  in  which  the  use  of  free- 


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FIG.  74. — Frick  Submerged  Ammonia  Condenser. 

falling  water  is  inadvisable  and  also  where  there  is  little  danger 
of  scale  forming,  is  the  double-pipe  condenser,  Fig.  75.  In  this 
one  pipe  is  placed  inside  of  another  one,  heavy  fittings  being 
used  to  connect  the  ends  so  that  cooling  water  may  be  passed 
through  the  inner  pipe  while  ammonia  is  condensed  in  the 
annular  space  between  the  two  pipes,  thus  using  the  air  as  a 


156 


ELEMENTS  OF  REFRIGERATION 


heat-absorbing  medium  as  well  as  the  water.  The  ammonia 
vapor  enters  at  the  top  at  A.  The  inner  pipe  passes  through 
this  special  casting  having  a  lead  packing-ring  stuffing-box. 
From  the  end  B  the  warmest  cooling  water  leaves.  The  am- 
monia passes  through  the  annular  space  between  the  two  pipes. 
At  the  end  C,  the  water  pipes  are  connected  by  the  return 
bend,  while  the  special  casting  supporting  the  two  successive 
sets  of  pipes  are  connected  and  the  ammonia  passes  to  the 
next  level  and  at  the  other  end  this  run  is  connected  to  the 
next  lower.  The  ammonia  and  water  pipes  are  connected  in 
this  way  until  D  is  reached,  from  which  the  liquid  ammonia 


Water 


Water 


FIG,  75, — Frick  Double  Pipe  Condenser. 

passes  out.  The  cold  water  enters  at  E.  The  special  return- 
bend  castings  are  arranged  so  that  the  water  pipe  is  held  in 
place  by  a  stuffing-box  and  by  means  of  a  properly  packed  joint 
a  projection  of  one  box  fits  into  a  groove  of  a  lower  one  and  thus 
connects  the  ammonia  channel  of  two  successive  lines.  The 
bends  are  held  together  by  bolts.  By  using  the  flanges  on  the 
outside  pipe  and  the  special  casting  F,  any  pipe  can  be 
removed  with  little  work. 

In  this  double-pipe  condenser  the  velocity  of  water  may  be 
increased  to  a  high  value,  thus  increasing  the  value  of  the 
coefficient  of  heat  transfer  K.  This  is  one  of  the  important 
features  of  the  double -pipe  condenser.  Its  main  use  has  been, 


TYPES  OF  MACHINES  AND  APPARATUS 


157 


however,  to  remove  the  free  water  from  the  installation  which 
results  in  dampness.  This  is  also  advisable  when  the  water  is 
to  be  used  for  other  purposes,  because  the  water,  which  is  under 
pressure,  may  be  delivered  to  any  point  after  warning. 

Fig.  76  shows  the  method  of  forming  double-pipe  condensers, 
as  recently  suggested  by  the  Philadelphia  Pipe-Bending  Co.     In 


Ammonia 


FIG.  76. — Philadelphia  Pipe  Bending  Co.  Double  Pipe  Condenser. 

these  condensers  a  tight  joint  is  made  by  packing  being  forced 
against  the  pipe  by  pressure. 

The  latest  improvement  in  condensers  is  to  have  a  liquid 
coating  on  the  ammonia  side  of  the  pipe,  as  it  has  been  the 
experience  of  those  familiar  with  this  apparatus  that  if  the  pipes 
are  covered  with  liquid  ammonia  they  will  transmit  more  heat 
per  degree  difference  per  hour  per  square  foot  than  they  will  if 
not  wetted.  The  York  Manufacturing  Company  obtains  this 
wet  condition  by  injecting  a  certain  amount  of  condensed  liquid 
from  the  condenser  back  with  the  compressed  vapor  on  its  way 
to  the  condenser,  using  an  injector  nozzle  to  take  up  the  liquid 


158 


ELEMENTS  OF  REFRIGERATION 


and  introduce  it  into  the  condenser  with  the  vapor.  Block 
accomplishes  the  same  thing  by  casting  a  ridge  in  the  return 
bends  of  his  condenser,  forming  a  dam  which  retains  a  certain 
amount  of  liquid  in  each  pipe.  In  this  way  increased  duty  from 
a  given  amount  of  surface  is  made  possible  by  the  presence 


Block  Type 


-  ^ 


Shipley  Type 
FIG.  77. — Block  and  Shipley  Condensers. 

of  liquid  inside.     This  liquid  is  carried  along  by  the  vapor 
flow. 

The  condenser  pipes  are  supported  by  vertical  pipe  supports 
shown  in  Fig.  78.  The  pipes  are  either  held  between  the  sup- 
ports or  on  brackets  projecting  from  the  side.  Bolts  are  used 
as  the  supporting  element  in  the  right-hand  type,  while  in  the 


TYPES  OF  MACHINES  AND  APPARATUS 


159 


middle  form  the  pipes  are  held  by  the  castings  when  they  are 
held  together  by  bolts. 

Separators.  The  separators  used  in  the  ammonia  systems 
for  scale  or  oil  separation  should  be  of  the  same  form  as  those 
used  in  engine  work,  but  with  heavy  walls  and  flanges  and  a 
strong  gasket  packing.  Fig.  79  illustrates  the  Triumph  Ice 
Machine  Co.  oil  separator.  The  incoming  vapor  and  oil  are 


i  I  ' 


FIG.  78. — Condenser  Pipe  Supports. 

discharged  by  means  of  a  cone  against  the  side  walls  of  the 
separator  and  the  oil  will  cling  to  the  wall  while  the  vapor  rises 
slowly  through  the  large  cross-section  of  the  cylinder  and  passes 
a  strainer  A  and  leaves  at  the  outlet  B.  The  oil  and  water  may 
be  drawn  off  at  the  drain  valve. 

Liquid  Receiver.  Liquid  receivers  are  usually  made  of 
pieces  of  extra  heavy  wrought-iron  pipe  with  flanged  heads 
welded  in.  They  are  strong  and  durable.  These  are  usually 
tested  to  500  Ibs.  air  pressure.  The  outlet  from  these  is  con- 


160 


ELEMENTS  OF  REFRIGERATION 


aected  to  the  bottom,  the  inlet  being  at  the  top.  In  some  cases 
the  discharge  from  the  condenser  enters  at  the  outlet  pipe,  and 
if  there  is  more  liquid  coming  from  the  condenser  than  that 
required  by  the  expander,  the  liquid  can  collect/ since  the  two 
valves  are  connected  by  an  equalizing  pipe. 

I    From 
jCompresaor 


To  Condenser 


FIG.  79. — Triumph  Oil  Separator. 

Brine  Cooler.  The  brine  cooler  is  an  apparatus  in  which 
heat  is  abstracted  from  the  brine  by  the  evaporation  of  the 
ammonia.  Usually  the  liquid  ammonia  is  admitted  at  the 
bottom  of  a  coil  of  pipe  and  the  vapor  resulting  from  the  evap- 
oration is  taken  off  from  the  top.  Around  this  coil  the  brine 
is  circulated,  or  in  some  cases  the  brine  is  in  the  coil  while  the 
ammonia  is  on  the  outside.  In  Fig.  19,  the  brine  cooler  is 


TYPES  OF  MACHINES  AND  APPARATUS 


161 


equipped  with  a  brine  coil,  the  liquid  ammonia  being  carried 
about  one-third  of  the  height  of  the  chamber  of  the  cooler.  It 
is  always  well  to  have  the  liquid  ammonia  in  contact  with  the 
metal  of  the  coil.  It  would  probably  yield  a  larger  heat  trans- 
fer in  Fig.  19  if  the  liquid  ammonia  were  sprayed  over  the 
brine  coil  from  the  top  of  the  chamber.  After  the  vapor  is 
formed  there  can  be  little  if  any  further  heat  removed,  so  that 
all  surface  in  contact  with  vapor  alone  is  of  little  value. 


FIG.  80. — Liquid  Receiver. 

In  the  Vogt  brine  cooler,  Fig.  81,  the  brine  is  passed  through 
the  horizontal  tubes  running  between  the  two  head  plates  in 
a  four-pass  course,  while  the  liquid  ammonia  is  introduced  at 
the  center  of  the  shell.  In  this  there  is  ample  heat  transfer  and 
the  surface  is  efficient. 

Fig.  76  would  represent  a  double-pipe  brine  cooler  as  well 
as  a  condenser  if  the  liquid  ammonia  were  placed  on  the  inside 
of  the  coil  and  the  brine  were  on  the  outside. 

Fig.  82  illustrates  a  triple-pipe  brine  cooler.  In  this,  liquid 
ammonia  enters  the  annular  space  between  the  two  inner  tubes 


162 


ELEMENTS  OF  REFRIGERATION 


of  a  set  of  three  consecutive  tubes  at  A .  This  space  of  one  line 
is  connected  to  the  space  on  the  next  level  by  the  special  return 
bend  B  in  the  same  manner  as  was  used  in  the  double-pipe  con- 
denser. This  is  then  repeated  at  alternate  ends  until  the  outlet 
C  is  reached.  At  this  point  is  the  suction  pipe  leading  to  the 
compressor.  The  brine  enters  at  D  and  passes  through  the  special 
casting  into  the  outer  annular  space  and  then  by  similar  castings 
at  E  it  enters  the  second  row,  finally  reaching  F}  at  which  point 
it  is  connected  to  a  return  bend  and  enters  the  center  of  the 
middle  tube.  Finally,  by  pipes  and  return  bend  it  reaches  the 


Outlet  f or  NH3  Vapor 


Brine 
Leaves 


FIG.  8 1.—  Vogt  Shell  Brine  Cooler. 


point  of  outlet  G.  Of  course  this  appears  to  be  partly  counter 
current  and  partly  parallel  flow,  but  it  must  be  remembered 
that  the  ammonia  at  all  parts  is  at  practically  the  same  tem- 
perature, since  there  is  little  drop  of  pressure  through  the  cooler. 
The  brine  cooler  shown  in  Fig.  83  is  that  built  by  the  Baker 
Co.  The  ammonia  lies  in  the  inclined  inner  tubes  and  is  intro- 
duced at  A,  passing  down  to  the  various  pipes.  The  vapor  is 
drawn  through  the  nozzle  B,  and  up  to  the  separator  C  to  the 
outlet  D.  Any  liquid  taken  up  is  removed  by  the  separator 
and  sent  back  through  E.  Brine  enters  at  F  and  leaves  at  G. 
The  connections  are  made  by  return  bends. 


TYPES   OF  MACHINES  AND  APPARATUS 


163 


164 


ELEMENTS  OF  REFRIGERATION 


TYPES  OF  MACHINES  AND  APPARATUS 


165 


Steam  Condensers.  The  ordinary  forms  of  steam  con- 
densers can  be  used  when  desired,  but  because  of  scale  troubles 
and  because  so  much  condensation  is  demanded  for  distilled 


FIG.  84. — Arctic  Oval  Flask  Steam  Condenser. 

water  in  ice  plants  this  is  done  at  atmospheric  pressure  in 
flask  condensers.  Fig.  84  is  made  of  sheet  iron.  Water  is  dis- 
charged over  the  surface  of  the  flask  and  condenses  the  steam 
within.  The  outside  and  inside  surfaces  of  the  condenser  may 


FIG.  85.— York  Steam  Surface  Condenser. 

be  cleaned  easily.  In  Fig.  85,  the  regular  shell  type  of  steam 
condenser  is  shown.  The  tubes  are  of  brass  and  although 
usually  held  in  place  by  soft  packing  they  are  expanded  in  the 
brass  tube  sheets  in  the  figure  shown.  The  left-hand  tube 


166 


ELEMENTS  OF  REFRIGERATION 


a 
t 

w 


TYPES   OF  MACHINES  AND  APPARATUS  167 

plate  with  the  water  head  is  allowed  to  expand  back  and  forth, 
thus  caring  for  expansion.  The  steam  fills  the  whole  inner 
chamber  of  the  shell  and  passes  around  the  left-hand  tube 
sheet  and  cap. 

One  of  the  latest  developments  of  refrigerating  machines 
is  the  Westinghouse-LeBlanc  evaporative  refrigerating  machine 
shown  in  Fig.  86.  This  was  described  by  Mr.  J.  C.  Bertsch 
before  the  American  Warehouseman's  Association  in  December, 
1915,  and  reprinted  in  Power  for  January  n,  1916.  In  this 
a  high  vacuum  is  maintained  in  the  evaporator  A  by  means  of 
a  series  of  steam  nozzles  B,  from  which  steam  at  a  high  velocity 
issued,  entraining  with  the  jet  any  air  or  vapor  which  may  be 
around  the  steam  jets  in  the  space  C.  By  making  the  nozzles 
long  enough  and  of  proper  shape  the  final  pressure  of  the  steam 
will  be  low  at  the  end  of  the  nozzle.  The  jets  of  steam  and 
entrained  air  and  vapor  enter  a  diffuser  D  where  the  velocity 
is  decreased  and  the  pressure  increased  to  such  a  value  that 
the  steam  and  vapor  may  be  condensed  by  the  water  supply 
in  the  condenser  E.  This  is  supplied  by  the  circulating  pump  F, 
the  water  coming  from  the  cooling  tower  G  which  has  received 
the  warmed  circulating  water  from  E.  The  air  pump  H  is 
a  Westinghouse-LeBlanc  centrifugal  air  pump  and  withdraws 
the  condensation  and  air  from  E.  The  water  of  condensation 
is  discharged  into  /  and  is  cooled  by  a  coil  and  flows  back  as 
sealing  water  for  the  pump. 

A  high  vacuum  existing  in  B  means  a  high  vacuum  in  A , 
and  consequently  the  brine  in  the  tank  /  is  sucked  up  into 
this  vessel  and  passes  through  the  perforated  plate  K  into 
an  inner  chamber,  where  it  is  broken  up  into  a  number  of  drops 
which,  falling  through  the  space  of  low  pressure,  are  subject  to 
evaporation  of  part  of  the  water  content.  This  of  course 
cools  the  brine  on  account  of  the  heat  of  evaporation  coming 
from  the  liquid,  and  by  the  time  it  reaches  the  bottom  of  the 
evaporator  it  is  cool  enough  to  be  circulated  by  the  brine  pump 
L  through  the  brine  system  Mt  after  which  the  warmed  brine 
is  discharged  into  the  surge  tank  or  receiver  /.  The  brine 
has  been  concentrated  in  A  by  evaporation  and  consequently 


168 


ELEMENTS  OF  REFRIGERATION 


water  must  be  added  in  /  to  reduce  the  concentration  by  the 
proper  amount.     This  is  done  by  the  float  valve.     The  various 


pumps  are  operated  on  the  same  shaft  by  a  steam  turbine. 
The  stuffing-boxes  of  the  brine  pump  are  water  sealed  to  keep 
out  the  air. 


TYPES  OF  MACHINES  AND  APPARATUS  169 

The  ejector  B,  composed  of  nozzles  and  the  diffuser,  are  such 
that  the  vacuum  carried  has  a  temperature  of  boiling  of  50°  below 
the  temperature  of  the  cooling  water  used  in  the  condenser.  If 
a  lower  temperature  is  desired,  say  70°  to  100°  below  the  cool- 
ing water,  two  of  these  are  used  in  the  series,  as  shown  in 
Fig.  87. 

Binary  refrigeration  is  the  name  given  to  the  use  of  a  mix- 
ture of  two  different  refrigerating  media  such  as  CC>2  and 
S02.  There  has  been  no  gain  shown  from  the  use  of  these. 
The  late  Mr.  E.  Penney  reports  in  the  Transactions  of  the 
American  Society  of  Refrigerating  Engineers  experiences  of 
himself  and  others  in  this  field. 

In  all  refrigerating  apparatus  the  use  of  thermometers  is 
important.  By  their  use  combined  with  that  of  the  pressure 
gauge  the  action  of  the  apparatus  may  be  known.  Thus  the 
condition  of  the  vapor  entering  the  compressor  may  be  known 
by  the  temperature  of  the  vapor  at  suction  pressure,  and  by 
thermometers  in  the  discharge  pipe  the  quality  of  the  suction 
vapor  may  be  known  by  the  amount  of  superheat  in  the  dis- 
charge gas.  The  water  and  brine  temperatures  tell  whether 
the  surfaces  are  dirty.  All  instruments  are  of  value  in  the 
proper  operation  of  a  plant. 

Cooling  Towers.  Where^  water  for  condensing  is  scarce 
some  method  of  cooling  is  necessary.  Cooling  towers  are  used 
for  this  purpose.  In  these,  water  is  allowed  to  flow  over  screens 
of  galvanized  wire,  glazed  tiles,  wooden  slats  or  some  other  form 
of  baffle  to  break  the  water  up  into  small  particles,  and  while 
in  this  condition  it  is  brought  in  contact  with  air,  which  will  be 
heated  and  absorb  some  moisture.  The  heating  of  the  air 
cools  the  water  and  the  evaporation  of  the  water  taken  up  by 
the  air  removes  more  heat.  This  is  the  principle  of  the  cool- 
ing tower:  the  heating  of  air  and  the  evaporation  of  part  of 
the  water  removes  sufficient  heat  to  cool  the  main  body  of  the 
water  so  that  it  may  be  used  again.  Of  course  the  only  place 
from  which  the  heat  of  vaporization  and  heat  for  the  air  can 
come  is  the  water. 

Fig.  88  illustrates  one  form  of  cooling  tower.    In  this  hot 


170 


ELEMENTS  OF  REFRIGERATION 


water  is  pumped  through  the  pipe  C  to  the  boxes  D  D  arranged 
at  the  top  of  the  tower  on  the  sides.  This  water  then  flows 
into  a  series  of  pipes  E,  which  are  slotted  on  top,  from  which 
it  flows  over  the  mats  B,  made  of  wire  screens.  The  air 


FIG.  88.— Cooling  Tower. 

blown  in  by  four  fans  F  meets  the  water  falling  in  small  drops 
over  the  screens.  Here  it  is  warmed  and  as  its  moisture  capac- 
ity increases  there  is  some  evaporation.  The  tower  proper 
is  made  of  sheets  of  steel  stiffened  by  angle  irons. 

If  a  sheet  metal  top  is  placed  above  the  top  in  the  form  of  a 


TYPES  OF  MACHINES  AND  APPARATUS 


171 


chimney,  the  fans  may  be 
omitted,  as  the  chimney 
effect  is  sufficient  to  cause 
the  proper  circulation  of  air. 
In  some  of  these  cooling  tow- 
ers glazed  tiles  on  end  form 
the  surface  over  which  the 
water  is  discharged.  Such 
a  tower  will  require  about 
0.2  sq.ft.  of  ground  area  per 
gallon  of  water  cooled  per 
minute. 

In  the  Hart  Cooling  Tower 
shown  in  Fig.  89  there  is  no 
fan.  The  tower  consists  of  a 
series  of  cooling  decks  C,  D, 
E,  F,  spaced  from  3  to  7  ft. 
apart,  depending  on  the 
amount  of  cooling  and  the 
quantity  of  water  to  be 
cooled.  The  cooling  decks 
are  made  up  of  trays  placed 
in  a  staggered  position  on  the 
upper  and  lower  flanges  of 
the  I-beam  supporting  the 
deck.  The  water  from  the 
supply  pipe  A  is  delivered 
through  a  set  of  spray  noz- 
zles B  above  the  first  set  of 
trays  and  there  falls  over  the 
successive  trays,  a  total  drop 
of  from  20  to  50  ft.  The 
splashing  of  the  water  as  it 
strikes  the  tray  causes  it  to 
fall  in  drops.  To  prevent 
the  spray  from  being  lost 
the  projecting  shields  G  are 


FIG.  89.— Hart  Cooling  Tower. 


172  ELEMENTS  OF  REFRIGERATION 

added.  These  not  only  catch  the  water  blown  away  but  they 
drive  the  air  down  into  the  tower  when  the  wind  is  blowing, 
causing  it  to  rise  through  the  center  or  on  the  other  side.  In 
this  way  the  wind  is  applied  to  operate  the  tower  and  in  calm 
weather  the  chimney  effect  from  the  heated  air  causes  a  cir- 
culation. The  moisture  in  windy  weather  is  usually  caught  on 
the  leeward  shield  and  delivered  to  the  next  deck.  This  and 
other  atmospheric  towers  occupy  from  i  to  if  sq.ft.  of  ground 
area  per  gallon  of  water  per  minute. 

In  Fig.  90  the  Thomas  nozzle,  used  to  spray  water  over 
a  basin,  is  shown.  In  this  the  hot  water  is  pumped  to  the 
nozzle  and  is  delivered  in  a  fine  spray.  The  discharge  orifice  is 
made  by  the  helical  opening  between  the  edges  of  a  strip  formed 
into  a  helix.  The  amount  of  opening  may  be  regulated  by 
the  central  spindle  operated  by  a  rod  which  controls  all  of  the 
nozzles  as  shown.  This  spray  of  water  warms  the  air  and 
permits  evaporation,  so  that  the  water  falls  to  the  tank  or 
pcnd  in  a  cooler  condition.  These  ponds  into  which  the  spray 
falls  should  have  about  2  sq.ft.  of  area  for  each  gallon  per  minute 
flowing. 

Another  method  of  cooling  water  is  to  discharge  it  into  a 
cooling  pond  and  to  cool  it  by  surface  evaporation,  the  hot 
water  entering  at  one  end.  If  the  pond  is  sufficiently  large  the 
water  is  cooled  by  the  time  it  reaches  the  other  end  of  the 
pond  or  reservoir  from  which  the  cooling  water  is  taken. 
These  ponds  should  have  about  70  sq.ft.  per  gallon  of  water  per 
minute  or  9  sq.ft.  per  horse-power  hour  per  day. 

In  all  of  these  arrangements  the  cooling  has  been  done 
by  the  heat  utilized  to  warm  air  and  evaporate  water.  The 
heat  to  do  these  two  things  has  to  come  from  the  water  and  hence 
the  water  is  cooled.  The  amount  of  moisture  which  the  air 
will  carry  is  called  the  amount  to  saturate  it.  The  air  will 
carry  no  more  moisture  at  a  given  temperature,  but  since  the 
amount  to  saturate  it  varies  with  the  temperature  the  capacity 
is  increased  by  warming  the  air.  Thus  if  at  75°  i  cu.ft.  of  air 
will  carry  9.4  grains  of  moisture,  the  quantity  is  increased  to 
14.9  grains  if  the  temperature  is  increased  to  90°.  If  air  at  75° 


TYPES  OF  MACHINES  AND  APPAEATUS 


173 


I 
f 

a 


174 


ELEMENTS  OF  REFRIGERATION 


contains  only  4.7  grains  per  cubic  foot  it  is  said  to  be  one-half 
saturated  and  it  could  take  up  4.7  grains  more  before  satu- 
ration is  reached.  If  at  the  same  time  the  temperature  were 
raised  to  90°  it  would  take  up  10.2  grains  before  reaching  sat- 
uration. Now  this  evaporation  removes  heat  and  it  is  one  of 


FIG.  91. — Wet  and  Dry  Bulb  Hygrometer. 

the  important  methods  of  removing  heat  in  a  cooling  tower. 
That  cooling  towers  may  evaporate  water  on  rainy  or  freez- 
ing days  when  the  air  is  saturated  is  seen  to  be  possible  by  the 
figures  above,  when  it  is  remembered  that  the  air  is  raised  in 
temperature  and  with  it  the  capacity  for  moisture.  Thus  air 
entering  at  75°  and  saturated  will  require  an  evaporation  of 
5.5  grains  per  cubic  foot  of  air  to  saturate  it  at  90°  if  this  is 


TYPES  OF  MACHINES  AND  APPARATUS  175 

the  temperature  of  leaving.  In  most  cases  the  air  will  leave 
at  or  near  the  temperature  of  the  hot  entering  water  and  hence 
the  capacity  for  moisture  is  increased. 

The  amount  of  evaporation  per  cubic  foot  of  air  will  depend 
on  the  amount  of  moisture  in  the  air  at  entrance.  The  condi- 
tion of  air  is  given  by  its  relative  humidity.  This  is  the  ratio 
of  the  amount  of  moisture  in  a  cubic  foot  of  air  to  that  required 
to  saturate  it,  as  was  stated  on  page  50.  The  instrument  used 
to  determine  this  is  called  a  hygrometer,  and  the  simplest  form 
is"the  wet  and  dry  bulb  thermometer  type  shown  in  Fig.  91.  In 
this  instrument  one  thermometer  has  a  wet  wicking  around 
its  bulb  and  on  whirling  these  in  the  atmosphere  the  amount 
of  evaporation  from  the  wicking  is  fixed  by  relative  humidity 
and  is  shown  by  the  drop  in  temperature.  By  reading  the 
wet  and  dry  bulbs  and  the  barometer  Carrier's  equation  (38) 
on  page  51  may  be  used  to  find  the  relative  humidity.  This 
formula  has  been  used  to  form  the  chart  of  Fig.  92,  so  that  the 
figure  may  be  used  to  find  the  relative  humidity  for  different 
temperatures  of  wet  and  dry  bulb,  since  barometric  changes 
are  not  sufficient  to  produce  much  variation.  The  chart  also 
gives  the  amount  of  moisture  per  cubic  foot  at  any  condi- 
tion. 

The  air  required  by  a  tower  for  a  given  amount  of  water 
is  found  by  equating  the  energy  in  the  substances  entering 
and  leaving.  It  is  found  that  the  water  may  be  cooled  to 
a  temperature  much  below  the  atmosphere  in  dry  weather, 
the  final  temperature  being  about  5°  above  the  wet  bulb 
temperature.  In  times  of  high  relative  humidity  of  70  or 
75%  the  water  will  leave  at  about  the  atmospheric  tem- 
perature, but  when  the  relative  humidity  is  40%  it  may  be 
from  10  to  15°  below  the  atmosphere,  showing  that  the  evap- 
oration of  water  has  produced  the  principal  cooling.  The 
leaving  temperature  may  be  taken  at  about  5°  above  the  wet 
bulb,  although  this  may  be  i°,  2°  or  even  o°  above  the  air  for 
high  humidity. 

To  compute  the  amount  of  water  cared  for  by  i  cu.ft.  of 
air  entering  the  following  method  is  used: 


176 


ELEMENTS  OF  REFRIGERATION 


150 


Difference  in' Temperature 
SO      42.    38    34  3Q        26       22     18      14.12    10     8     6 


30 


4  6 

Relative  Humidity 


70 


FIG.  92.— Relative  Humidity  and  Moisture  according  to  Carrier's  Formula. 

Let  tcd  =  temperature  of  dry  bulb  in  air  entering; 
taw  =  temperature  of  wet  bulb  in  air  entering; 
t'Cd  =  temperature  of  dry  bulb  in  air  leaving; 
t'aw  =  temperature  of  wet  bulb  in  air  leaving; 

/  =  temperature  of  water  at  exit; 

t'  =  temperature  of  water  at  entrance; 

p  =  relative  humidity  at  entrance  of  air; 

p  =  relative  humidity  at  exit  of  air; 
Bar  =  barometric  pressure  in  pounds  per  square  inch; 

p  =  steam  pressure  at  temperature  taa\ 


TYPES  OF  MACHINES  AND  APPARATUS  177 

pf  =  steam  pressure  at  temperature  t  'ad; 

m  =  weight  of  i  cu.ft.  saturated  steam  at  tad', 

m'  =  weight  of  i  cu.ft.  saturated  steam  at  t'ad\ 

M  =  weight  of  water  entering  per  cubic  foot  of  air  at 

entrance  ; 
Assume: 


—     — 

I  aw  —  *  ad  — 

or 


Then 

Moisture  per  cubic  foot  of  air  at  en  trance 

Volume  of  air  at  exit  per  cubic  foot  at  entrance 

i44(Bar-pj»)      53.35(^+460)  =  y,  ,  •, 

53-35  X(/ 


Moisture  in  air  at  exit  per  cubic  foot  at  entrance 

Bar  —  pp     t'ad  +460        t,,  /     \ 

=^        vX;  --  ^-Xm'  =  m"  ......     (10) 

Bar  —  p      tad+46o 

Moisture  absorbed  =  m"  —  mp  =  m"f  .....     (n) 
Energy  entering  tower: 


With  i  cu.ft.  air 


+  )=£4i44(Baf_     }_ 


0.4  ,  0.4 

With  m  Ibs.  moisture  =  m$iJ.      .     .     .    .     (13) 
With  M  Ibs.  of  water  =Mq'tJ  .....     (14) 
Energy  leaving  tower: 
With  air  of  V  cu.ft. 


(,5> 


178  ELEMENTS  OF  REFRIGERATION 

With  m"  Ibs.  of  moisture        =m'"i'J.     .     .     ,      .     (16) 
With  (M-m"f)  Ibs.  of  water  =  (M-m'"}qrJ.    .     .     (17) 

In  these  i'  is  the  heat  content  of  vapor  in  saturated  or  super- 
heated condition  and  qf  is  the  heat  of  liquid. 

By  equating  these  the  quantity  M  may  be  found.  This 
gives  the  amount  of  water  per  cubic  foot  of  air  entering,  or  the 
reciprocal  will  give  the  cubic  feet  of  air  per  pound  of  water 
entering.  In  this  way  the  air  for  a  given  amount  of  water  may 
be  found  and  the  fan  to  introduce  this  air  or  the  chimney  to 
suck  this  air  may  be  computed.  The  evaporation  per  pound 


m'" 


entering,  -rp,  will  give  the  amount  of  make-up  necessary. 

In  designing  nozzles  for  cooling  fountains  the  assumption 
may  be  made  that  the  evaporation  will  reduce  the  temperature 
provided  the  final  temperature  is  above  the  wet  bulb  tem- 
perature. The  number  of  nozzles  may  be  found  from  the 
quantity  of  water  by  using  the  following  data: 

The  capacity  of  the  spray  nozzles  of  the  Thomas  form  is 
150  gallons  per  minute  under  4  Ibs.  per  square  inch  pressure. 
For  ordinary  spray  nozzles  the  discharge  in  gallons  per  minute 
is  given  by  the  table : 

Size,  inches.  5  Ibs.  pressure.  10  Ibs.  pressure. 

i-5  IS  21 

2 . 0  40  60 

2.5  70  90 

3.O  1 2O  140 

A  velocity  of  5  ft.  per  second  at  the  entrance  to  the  nozzle 
will  give  the  discharge  at  5  Ibs.  pressure.  The  tank  or  reser- 
voir used  with  these  nozzles  should  have  about  i\  sq.ft.  of  sur- 
face for  every  gallon  per  minute.  When  the  weather  is  warm 
a  second  spraying  is  necessary  in  successive  nozzles  over 
separate  reservoirs. 

The  cooling  pond  may  be  made  of  such  a  size  that  i  sq.  ft. 
will  care  for  3^  B.T.U.  per  hour  per  degree  difference  in  tern- 


TYPES  OF  MACHINES  AND  APPARATUS  179 

perature  between  air  and  water;  70  sq.ft.  per  gallon  per  min- 
ute of  water  to  be  cooled  has  been  suggested  for  the  area  of  the 
pond. 

Safety  Devices.  There  are  several  devices  which  are  in- 
stalled in  all  plants  using  poisonous  or  suffocating  gases  to  pre- 
vent loss  of  life  and  make  the  operation  of  the  plant  possible. 
One  of  the  important  ones  is  a  helmet  to  wear  over  the  head  when 
it  is  necessary  to  enter  a  room  filled  with  fumes  to  repair  a  break, 


FIG.  93. — Improved  Vajen  Helmet. 

to  shut  a  valve,  or  to  rescue  a  person.  There  are  several  of  these 
in  use.  One  of  them  is  shown  in  Fig.  93.  The  Vajen  helmet 
weighs  10  Ibs.  and  fits  over  the  shoulders,  being  strapped  tight 
on  a  wool  gasket.  The  weight  is  carried  by  the  shoulders,  leav- 
ing the  head  free  to  turn.  The  air  contained  in  the  reservoir 
under  pressure  is  sufficient  for  one-half  to  one  and  one-half 
hours'  use.  The  helmet  is  made  of  fire  and  water-proof  mate- 
rials, and  by  the  large  double-plate  mica- covered  openings 
guarded  by  cross  bars  one  can  easily  see  to  work.  Rotary 
cleaners  are  provided  to  clean  these  if  obscured  by  smoke  or 


180  ELEMENTS  OF  REFRIGERATION 

moisture.  Telephonic  ear  pieces  with  special  sounding  dia- 
phragms enable  the  operator  to  hear  distinctly  and  a  whistle 
on  front  of  the  helmet  makes  it  possible  for  the  operator  to 
signal  others. 

The  air  reservoir  is  charged  in  two  minutes  by  an  air  pump, 
and  although  this  is  a  short  time  the  reservoir  should  be  kept 
charged.  By  opening  the  valve  on  the  top  reservoir  air  is 
discharged  into  the  helmet  in  front  of  the  nostrils  of  the  wearer. 
This  is  above  atmospheric  pressure  and  forces  the  gases  from 
respiration  through  the  absorbent  lambs-wool  collar  gasket  and 
prevents  the  entrance  of  other  gases. 

The  top  of  the  helmet  is  braced  to  protect  the  wearer  against 
danger  from  falling  objects,  as  the  helmet  is  intended  for  use 
in  fires  or  in  chemical  works. 

To  guard  against  fatal  results  from  accidents  rules  are 
made  for  the  management  and  installation  of  refrigerating 
plants  in  large  cities.  Among  certain  rules  formulated  by  the 
city  of  New  York  the  following  are  noted: 

It  is  unlawful  to  operate  a  plant  with  gases  under  pressure 
without  a  license  from  the  fire  commissioner. 

An  emergency  pipe  with  valve  outside  to  discharge  gases 
into  water  sufficient  to  absorb  full  charge  is  to  be  installed. 

All  refrigerating  machines  must  be  equipped  with  safety 
valves  to  discharge  at  300  Ibs.  per  square  inch  pressure  for 
ammonia,  1400  Ibs.  for  carbon  dioxide,  100  Ibs.  for  sulphur 
dioxide  and  100  Ibs.  for  ethyl  chloride.  These  are  to  discharge 
into  emergency  pipes  or  to  the  low-pressure  side  of  the  system. 

There  must  be  provisions  for  exit  into  the  outside  air  or  to 
a  hall  from  which  gas  can  be  excluded  for  all  rooms  when  the 
pressures  are  above  the  following  limits: 

Ethyl  chloride 40  Ibs.  per  square  inch 

Sulphur  dioxide 60  " 

Ammonia 100  l ' 

Carbon  dioxide 500  1 1 

All  fittings  are  to  be  tested  to  twice  the  maximum  pressure 
and  pipes  to  three  times  the  maximum. 


TYPES  OF  MACHINES  AND  APPARATUS  181 

No  open  flames  are  allowed  in  any  rooms  having  pressure 
pipes. 

Helmets  must  be  installed  in  all  plants. 

Pipes  are  to  be  tagged  showing  kind  of  substance  within. 

Storage  of  extra  refrigerating  substance  will  not  amount 
to  more  than  10%  of  capacity.  The  cylinders  cannot  be  kept 
in  the  boiler  room  but  in  some  cool  place. 

When  the  plant  has  a  capacity  of  more  than  3  tons  the 
operator  must  have  a  certificate. 

The  United  States  Interstate  Commerce  Commission  has 
provided  certain  rules  relating  to  the  cylinders  for  the  ship- 
ment of  gases  under  pressure.  Some  of  these  are  as  follows: 

Cylinders  must  comply  with  requirements  and  be  made  of 
lap-welded  pipe  of  soft  steel  of  best  welding  quality.  They 
may  be  made  seamless.  The  heads  should  be  welded  in.  The 
carbon  is  limited  to  0.20%,  phosphorus  0.11%,  and  sulphur 
0.05%.  The  cylinders  must  stand  1000  Ibs.  per  square  inch 
in  a  water  jacket  to  give  extension  which  must  not  be  over 
10%  of  volume.  Cylinders  must  stand  flattening  out.  They 
must  be  annealed.  The  cylinders  must  be  stamped  with  name 
of  owner.  Gases  which  combine  may  not  be  shipped  in  one 
cylinder.  Each  cylinder  must  be  tested  once  in  five  years 
under  pressure.  Test  pressure  is  one  and  one-quarter  times 
the  pressure  of  vapor  at  130°  F.,  except  for  carbon  dioxide 
cylinders,  which  are  tested  to  3000  Ibs.  per  square  inch. 


CHAPTER  V 
HEAT  TRANSFER,  INSULATION  AND  AMOUNT  OF  HEAT 

HEAT  is  transferred  by  radiation,  convection  and  conduc- 
tion. In  the  first  method  a  body  starts  a  vibration  in  the 
ether,  which  is  transmitted  by  it  to  another  body  which 
receives  this  energy  of  vibration  and  changes  it  into  heat 
energy  of  the  body.  This  form  of  transmission  depends  on  the 
difference  of  the  fourth  powers  of  the  temperatures  of  the  two 
bodies.  Although  important  in  some  cases,  radiation  does 
not  play  an  important  part  in  refrigeration.  In  the  second 
method,  particles  of  some  medium,  as  air,  are  heated  by  a  hot 
body  and  then  by  the  bodily  transfer  of  these  heated  particles 
the  energy  received  by  them  is  carried  to  a  cooler  body,  which 
abstracts  the  heat.  This  method  of  heat  transfer  is  one  used 
for  some  types  of  refrigeration.  The  third  method  is  that 
in  which  heat  energy  is  applied  to  the  molecules  of  one  part 
of  a  body,  and  then  by  transmitting  this  energy  to  adjacent 
molecules  the  energy  is  gradually  conveyed  through  the  body. 
It  is  in  this  manner  that  heat  is  taken  from  cold  storage  rooms 
by  the  brine  or  ammonia,  or  heat  is  added  to  the  room  from 
the  atmosphere.  The  last  two  methods  of  heat  transfer  must 
be  examined  in  detail. 

If  M  Ibs.  of  substance  are  heated  at  constant  pressure 
from  a  temperature  ti  to  /2  when  the  specific  heat  is  cp,  the  heat 
required  to  do  this  is 

Q  =  Mcp(t2  — 1\)      .     .     .     ...     .     .     (i) 

or 


(2) 


The  first  is  correct  if  cp  is  constant,  or  is  the  mean  value 
of  Cp,  and  the  second  is  correct  if  cp  is  a  variable.     The  substance 

182 


HEAT  TRANSFER,  INSULATION          183 

usually  employed  is  air,  and  although  cp  for  air  is  not  constant, 
the  variation  for  the  temperature  ranges  used  in  refrigerating 
problems  is  negligible.  Hence  the  first  formula  may  be  used 
with  a  value  of  0.24  for  cp.  If  now  the  air  is  conducted  to  a 
room  or  cooler  and  is  brought  back  to  the  temperature  /i,  the 
same  amount  of  heat  must  be  abstracted,  and  so  the  heat  Q 
taken  from  the  first  body  has  been  given  to  a  second  body 
and  the  air  or  carrying  medium  has  been  left  in  its  original 
condition.  This  heat  has  been  carried  by  convection. 

In  conduction  the  heat  transmitted  depends  on  the  mate- 
rial, the  temperature,  the  cross-section  of  the  material  and 
the  length  of  the  path.  The  equation  for  conduction  is  similar 
to  that  for  the  flow  of  the  electric  current. 


F  =  area  of  cross-section  in  square  feet; 

/  =  length  of  path,  or  thickness,  in  feet; 

/  =  temperature  on  either  side  in  deg.  F.; 
C  =  constant  of  conduction,  or  B.t.u.  per  hour  per  square 
foot  per  degree  for  i  ft.  thickness. 

The  value  of  C  has  been  determined  by  various  experiments, 
and  by  its  use  the  amount  of  heat  conducted  can  be  predicted. 
•  When  heat  is  transmitted  through  partitions,  it  is  difficult 
to  compute  the  amount  of  heat  transmitted  because  it  is  hard  to 
determine  the  temperatures  at  the  edge  of  the  plate  on  account 
of  films  of  fluid  which  cling  to  the  surface  and  make  heat  trans- 
mission difficult.  Thus,  if  heat  from  the  gases  of  a  boiler 
is  to  be  taken  into  the  water  in  contact  with  the  tube,  and 
Eq.  (3)  is  used  to  compute  the  probable  heat  transfer,  using 
the  C  for  steel  of  thickness  /,  and  substituting  the  temperatures 
of  the  gas  and  boiling  water,  the  heat  would  be  equal  to  more 
than  250  times  the  amount  actually  transmitted.  The  great 
reduction  is  due  to  the  effect  of  the  films  of  gas  and  water 
fvhich  cling  to  the  sides  of  the  tube  and  cut  down  the  heat  trans- 
mitting power.  A  thin  film  of  gas  or  water  has  a  much  greater 


184  ELEMENTS  OF  REFRIGERATION 

resistance  than  a  thick  wall  of  metal.  The  transmission  through 
the  gas  or  water  film  could  be  computed  if  the  thicknesses  were 
known,  but  these  are  quantities  which  vary,  depending  largely 
on  the  velocity  of  the  fluids  over  the  surface,  and  also  upon 
the  viscosity  of  those  fluids.  On  account  of  this  action  exper- 
iment has  been  resorted  to  to  determine  a  constant  K,  which 
is  the  amount  of  heat  transmitted  per  square  foot  per  hour 
per  degree  difference  in  temperature  for  the  surfaces  trans- 
mitting heat.  Since  in  many  cases  the  surface  effects  are  the 
controlling  factors,  and  not  the  main  body  of  the  partition, 
the  thickness  of  the  partition  will  not  enter  into  the  expression. 
With  K  the  equation  for  heat  transmitted  becomes 


(4) 


K  =  E.t.u.  per  square  foot  per  hour  per  degree; 
JF  =  area  in  square  feet; 
/  =  temperature  in  degrees  F. 

The  value  of  K  is  now  determined  experimentally  for  the 
transmission  of  heat  through  metal  walls  in  condensers, 
absorbers  and  such  apparatus,  and  it  is  found  that  as  the  veloc- 
ity of  the  liquids  on  either  side  increases  the  value  of  K 
increases.  It  is  also  found  that  for  greater  differences  in 
temperature  the  value  of  K  changes,  becoming  less  usually 
as  the  temperature  difference  increases.  For  the  temperature 
differences  usually  found  in  ammonia  and  steam  condensers, 
brine  coolers,  feed-water  heaters  and  such  apparatus,  the 
value  of  K  found  in  experimental  work  with  a  given  set  of 
temperature  conditions  may  properly  be  used  with  other  tem- 
perature conditions  since  there  would  not  be  enough  change 
in  temperature  difference  to  affect  the  value  of  K. 

If  K  is  a  constant  and  the  temperatures  on  one  or  both  sides 
change  along  the  length  of  the  surface  it  is  necessary  to  find 
the  mean  temperature  difference  in  terms  of  the  temperatures 
at  the  ends  of  each  surface.  Suppose  that  thl  and  th2  are  the 
temperatures  on  the  warm  side  at  entrance  and  exit  and  that 
tci  and  tcz  are  the  temperatures  at  the  same  ends  on  the  cool 


HEAT  TRANSFER,  INSULATION         185 

side  of  the  surface.  At  any  point  x  the  temperatures  on  the 
two  sides  will  be  thx  and  tcx.  The  amount  of  heat  transmitted 
through  the  differential  surface  at  this  point  measuring  from 
first  end  will  give  a  rise  in  temperature  of  dtc  to  the  cool  sub- 
stance of  Mc  pounds  per  second,  and  there  will  be  a  drop  dt* 
on  the  warm  side  where  Mh  Ibs.  per  second  flow.  Hence 

KdF(thx-tCx)  =  -$6ooMhchdth=±3()ooMcccdtc.       .     (5) 

As  dF  increases  dfa  decreases  and  dtc  increases  for  parallel 
flow  but  decreases  for  counter  current  flow.  The  upper  sign 
refers  to  parallel  current  flow. 


ccc 
^=±3600-  ........     .     (6) 

Now 

or 

MnC* 

Mccc~      thl-th2' 
Also 

thl  -  foj  =  ^  Mccc[tCl  -  tcx]  . 


f  , 
(9) 


186  ELEMENTS  OF  REFRIGERATION 


A/2 


Afe 


Afc 
geA<!      Heat  added 


Now 

Heat  =  FJfiT(mean  A/). 

Hence 

T»T  A/2—  A/i  A/I—  A/2  /     \ 

MeanA/  =  —  -  -  -     or     —  -  -  .....     (14) 


This  then  is  the  value  for  mean  A/  to  use  in  formula  (4) 
for  the  solution  of  heat  transfer  problems. 


If  K  has  the  value  ^  = 


This  leads  to 


/)1-nXF.   .     ,     .     (17) 

The  values  of  K  given  by  various  authorities  are  as  fol- 
lows: 


^HEAT  TRANSFER,  INSULATION 


187 


K=   3  from  gas  to  gas; 
=   5  from  liquid  to  gas; 
=  250  from  liquid  to  vapor; 
=  400  from  liquid  to  liquid. 

The  average  values  can  be  used  in  case  of  need,  but  more 
exact  values  are  given  below.  These  show  the  effect  of  velocity 
and  also  show  the  need  of  special  experiments. 

Values  of  K.  For  ammonia  condensers  of  the  double  type 
form,  the  values  of  K  as  determined  by  R.  L.  Shipman  in  the 


400 


•300 


bo 
• 
•o 

I 

3100 


345678 
Velocity  Feet  per  Sec.  of  Water 


10 


11 


FIG.  94. — Shipman's  Values  of  K  for  Double  Pipe  Condensers. 


Transactions  of  the  American  Society  of  Refrigerating  Engi 
neers  for  1907  are  given  in  Fig.  94.     The  values  of  K  may  be 
taken  from  these  curves.     In  Fig.  95  the  values  of  K  for  brine 
coils  are  given  at  different  velocities.     The  first  of  these  curves 
has  the  equation 


(18) 


Ww  =  velocity  of  water  in  feet  per  second. 
The  equation  of  the  second  curve  for  brine  coils  is 


(19) 


188 


ELEMENTS   OF  REFRIGERATION 


Some  allow  100  for  K  for  double-pipe  coolers  and  condensers. 
Fred  Ophuls  has  stated  that  his  experiments  indicate  that 
for  double-pipe  condensers 


K 


(20) 


Wm  —  relative  mean  speed  of  ammonia  and  water  in  feet 
per  second.  The  velocity  of  the  ammonia  may  be  taken  as 
one-half  the  velocity  of  the  vapor  at  inlet  to  condenser. 


200 


150 


100 


300  400 

Feet  per  Min.  Brine 

FIG.  95. — Shipman's  Values  of  K  for  Brine  Coils. 


He  also  gives  the  following  : 

For  condensers   of   the   Block   type   and   for   atmospheric 
single-pipe  condensers  the  experimental  results  were  given  by 


(21) 


Wv  =  velocity  of  vapor  at  entrance  in  feet  per  second. 
For  the  cooling  of  the  superheated  vapor  the  constant  falls 
off,  being 

(22) 


^5  =  mean  speed  of  superheated  vapor  in  feet  per  second. 

Thomas  Shipley  gives  60  as  the  value  of  K  for  open  atmos- 

pheric condensers  and  300  as  the  value  in  the  Shipley  con- 


HEAT  TRANSFER,  INSULATION          189 

denser,  in  which  part  of  the  liquid  ammonia  is  forced  through 
with  the  incoming  vapor  so  as  to  wet  the  inside  surface  of  the 
condenser.  (See  Fig.  77.) 

Rules  used  in  practice  may  be  mentioned.  One  requires 
40  sq.ft.  of  open  air  condenser  surface  per  ton  of  refrigerating 
capacity  and  25  sq.ft.  for  submerged  condensers.  These  rules 
are  to  be  used  as  checks.  In  many  cases  18  sq.ft.  are  used 
per  ton  while  Block  condensers  have  been  operated  success- 
fully at  8  sq.ft.  per  ton. 

For  brine  coolers  and  brine  tanks  the  value  of  K  would 
be  50,  although  experiment  must  be  made  to  find  the  effect  of 
velocity  more  accurately. 

For  brine  coolers  Fred  Ophuls  and  V.  R.  H.  Greene  found 
that  although  the  values  of  K  from  their  experiments  were  not 
correctly  given  by  any  equation,  their  experiments  when  there 
is  no  superheat  were  best  represented  by 


K=  20.6V  0.$2lWa  +  Wb  .....       (220) 


Wa  =  velocity  of  ammonia  vapor  at  outlet  in  feet  per  second; 

Wb  =  velocity  of  brine  in  feet  per  second. 

When  this  ammonia  leaves  in  a  superheated  condition  the 
coefficient  is  changed  to  15.2. 

Levey  gives  as  a  rule  the  allowance  of  55  sq.ft.  of  expansion 
coil  per  ton  of  refrigeration  with  at  least  60  cu.ft.  of  capacity 
of  brine  in  tank  per  ton.  This  is  only  a  check  on  the  computa- 
tion for  K.  The  York  Mfg.  Co.  uses  108  sq.ft.  of  direct  expan- 
sion coil  per  ton  of  capacity.  This  is  250  [lineal  feet  of  ij-in. 
pipe  to  ton.  With  ordinary  piping,  without  flooding  the 
coils  with  ammonia,  350  ft.  of  pipe  may  be  used.  Some  have 
found  that  the  formation  of  ice  around  the  expansion  coil  in 
a  brine  tank  increases  the  rate  of  heat  transmission;  i  in. 
of  ice  increased  the  transmission  to  1000  B.t.u.  per  foot  per 
hour  of  ij-in.  pipe  and  2  ins.  trebles  this. 

For  liquid  fore-coolers  the  constant  is  given  by 

#  =  1.22717.     .    ,_.    .....     (23) 

W  =  velocity  of  the  liquid  in  feet  per  second. 


190 


ELEMENTS  OF  REFRIGERATION 


The  value  of  K  for  coils  in  rooms  from  brine  or  ammonia 
to  air,  should  be  taken  as  about  five,  although  Siebel  states  that 
ten  could  be  used.  Since  ice  and  snow  are  deposited  on  pipes 
in  refrigerated  rooms,  these  constants  cannot  be  used  and  the 
allowances  employed  in  practice  are  given.  These  are  as 
follows : 


For  direct-expansion  pipes 
(Siebel) 


For  brine  pipes  (Siebel) 


For  brine  pipes  (Levey)  small 
rooms 


Room  1000  to  10,000  cu.ft. 


Rooms  over  10,000  cu.ft. 


ft.  of  2-in.  pipe  for  10  cu.ft.  of  space  at  10°  F. 


40 
60 
16 

6 
26 
60 

i 
4 
8 

2 

6 
14 

3 

9 

16 


32 
50 
35 
10 
32 
50 
o 

10 

32 

o 

10 

32 

o 

10 

32 


About  50  sq.ft.  of  pipe  will  care  for  i  ton  of  refrigeration 
and  100  sq.ft.  of  pipe  for  i  ton  of  ice  manufactured. 

INSULATION 

When  the  thickness  of  insulation  is  great  or  when  the 
resistance  of  the  internal  portions  becomes  appreciable  when 
compared  with  the  resistance  at  the  surface,  the  Eq.  (4)  is  used 
to  find  the  heat  transmitted  by  the  partition,  and  K  is  com- 
puted for  the  various  elements  of  the  partition.  This  is  the 
problem  of  heat  transfer  through  walls. 

The  heat  loss  from  rooms  is  made  up  of  several  parts.  There 
are  radiation  and  conduction  from  walls,  windows  and  doors 
and  convection  losses  due  to  warming  of  the  leakage  air,  or  the 
air  for  ventilation.  There  is  a  gain  of  heat  derived  from  per- 
sons or  apparatus  used  in  the  room,  or  from  sources  of  light 
of  various  kinds.  The  heat  loss  through  walls  partakes  of 
the  nature  of  radiation  and  conduction.  The  principal  loss 
is  made  up  of  transmission,  which  is  found  to  depend  on  the 


HEAT  TRANSFER,  INSULATION 


191 


difference  of  temperature  and  therefore  it  is  similar  to  con- 
duction rather  than  radiation,  which  depends  on  a  higher 
power  of  the  temperatures.  The  general  form  in  which  this 
heat  loss  is  given  is 

H  =  KF(tt-t0),        />..;.;.-    .     (24) 

where  F  =  area  in  square  feet; 

#  =  heat  transmitted  per  square  foot  per  hour  per  degree 

difference  of  temperature  in  B.t.u.; 
/t=room  temperature  in  degrees  F.; 
to  =  outside  temperature  in  degrees  F.; 
H  =  B.t.u.  transmitted  per  hour. 

The  value  of  K  depends  upon  several  factors:  the  surface, 
thickness  and  kind  of  material,  air  spaces  and  condition  of 
air  at  surface.  It  also  depends  on  temperature  difference, 
but  since  the  temperature  differences  are  not  large,  this  effect 
may  be  neglected.  The  following  German  method  from  H. 
Rietschel's  Leitfaden  zum  Berechnen  und  Entwerfen  von 
Luftungs-  und  Heizungs-Anlagen  is  usual  for  future  reference 
for  cases  which  have  not  been  calculated  in  the  text. 

The  rate  of  transmission  of  heat  through  any  substance 
depends  upon  the  thickness 
and  on  the  difference]  of  tem- 
perature. If  for  instance  the 
wall  shown  in  Fig.  96  is  made 
up  of  several  thicknesses,  and 
the  temperatures  are  those 
marked,  the  equations  for  the 


3     I 


FIG,  96.— Wall  Section. 


transmission  of  heat  through 
each  section  must  give  the 
quantity  of  heat  transmitted 
by  the  wall,  and  these  therefore  must  be  equal  to  each  other. 

The  amount  of  heat  conducted  by  any  material  per  square 
foot  of  cross-section  varies  directly  with  the  temperature  dif- 
ference and  inversely  with  the  length.  This  gives 


(25) 


192  ELEMENTS  OF  REFRIGERATION 

where  C  is  the  constant  of  conduction  for  i  ft.  thickness  in 
B.t.u.  per  square  foot  per  degree,  /  is  the  thickness  in  feet 
and  t\—  /2  is  the  difference  of  temperature.  Using  this  for  the 
wall  shown  in  Fig.  96,  the  following  results: 

Z7      kl/.f         ,//  \       ^2/,r         ./  \       ^3/,r         ,//  \  /    /;\ 

H  =  —(ti-t    2)=—(t2-t3)=—(t3-t   o).       •       (20) 
/I  /2  /3 

At  the  surface  of  any  material  there  is  to  be  found  a  temperature 
different  from  that  of  the  contiguous  space  and  it  is  this  differ- 
ence which  determines  the  flow  of  heat  at  the  surface. 
At  the  surface  the  same  formula 


holds,  but  since  /  is  difficult  to  find,  the  quantity  -  has  been 

l 

replaced  by  a  and  experiment  is  used  to  find  the  value  of  this 
for  different  materials  and  conditions  of  the  surface.  If  a 
is  the  coefficient  of  transmission  per  square  foot  per  hour 
per  degree  across  this  surface,  this  becomes  at  different  sur- 
faces: 


The  values  of  H  in  the  sets  above  are  all  the  same  quantity, 
hence  solving  for  temperature  differences  and  adding,  the  fol- 
lowing results: 


.       (28) 

_ai     Ci     a2     as     L2    Cs     a4J 
Now 

X  X  =  ^L.         .      • 

Hence 

^T— - — : — r — ; ; r-  •    •    •    (29) 


HEAT  TRANSFER,  INSULATION 


193 


VALUES  OF  C 


Air,  still o .  03 

Air  in  motion o .  09 

Asbestos  paper 0.04 

Blotting  paper o .  04 

Brass.  .  . 61.00 

Brickwork 0.46 

Building  paper 0.08 

Cement o .  40 

Charcoal o.  03 

Copper ' 202.00 

Coke 0.05 

Cork,  compressed 0.022 

Cork,  granulated 0.03 

Cotton 0.03 

Feathers o.  040 

Felt 0.02 

Glass 0.54 

Hair  felt.  .  0.026 


Lead 20.00 

Limestone 1.35 

Lith o .  028 

Marble,  fine i .  88 

Mortar  and  plaster o .  46 

Mineral  wool 0.05 

Oak 0.13 

Pine  (along  the  grain) o.  n 

Pine  (across  the  grain) 0.06 

Plaster  of  Paris 0.34 

Sandstone 0.87 

Sawdust 0.03 

Shavings 0.05 

Slate. o.  19 

Terra-dotta o.  54 

Tin 35-6o 

Wool o .  03 

Zinc 74-oo 


The  values  of  the  quantities  a,  as  given  from  Grashof  and 
Rietschel,  are  of  the  form 


(30) 


IO,OOO 


d  and  e  are  constants,  d  depends  on  the  condition  of  the  air 
around  the  surface  and  e  depends  upon  the  material.  T  is  the 
temperature  difference  between  the  air  and  the  surface  at  any 
point. 

To  determine  the  quantity  T,  a  method  of  approximation 
is  used  until  by  practice  one  knows  what  to  expect.  The  value 
of  the  term  involving  T, 


10,000 

is  small,  hence  for  a  first  approximation  this  term  may  be 
neglected  and  the  value  of  the  various  #'s  may  be  found. 
These  may  then  be  used  to  find  K. 


(31) 


194  ELEMENTS  OF  REFRIGERATION 

after  this  is  known  the  following  results: 


=  etc.  , 
T  =  ti-t\     or    /"o-/0. 

These  equations  give  the  first  approximations  for  T. 

In  this  way  after  T  is  found  as  a  first  approximation,  the 
value  may  be  used  to  find  a  second  value  of  a  and  then  a  new 
value  for  T.  In  this  way  two  or  three  trials  will  lead  to  the 
correct  result. 

In  any  case  the  value  of  T  is  small  and  this  is  true  par- 
ticularly for  thick  walls  or  in  cases  in  which  h—to  is  a  small 
quantity. 

Rietschel  gives  results  used  in  practice  for  the  value  of  T 
for  masonry  walls.  These  may  be  put  into  the  form  of  an 
equation, 

T  =16.2  —  4.001  .......     (32) 

This  may  be  used  for  masonry  walls  with  air  spaces  where  / 
is  the  sum  of  the  various  thicknesses  of  masonry,  although 
the  result  is  slightly  too  large  in  this  case,  as  the  quantity 
K(ti—to)  is  smaller  than  for  a  solid  wall  of  the  combined 
thickness. 

For  a  single  glass  T  is  taken  as  £(/i—  /o),  while  for  double 
windows  \(t^  —  h)  is  taken  at  each  surface,  since  glass  is  so 
thin  there  is  practically  no  temperature  drop  in  it,  the 
main  resistance  being  at  the  surface. 

The  value  of  T  for  wooden  floors  is  given  as  r  =  i.8°  F. 
The  values  of  d  as  given  from  Grashof  are  as  follows: 

VALUES  OF  d 

Air  at  rest  as  in  rooms  or  channels  ............  ..........................   0.82 

Air  with  slow  motion  as  over  windows  ............  .....................   i  •  03 

Air  with  quick  motion  as  outside  of  building  ............................   1-23 

The  values  of  the  coefficient  e  are  determined  by  Rietschel 
as  follows: 


HEAT  TRANSFER,  INSULATION 


195 


VALUES  OF  e 


Brass,  polished 0.05 

Brickwork  and  masonry o.  74 

Cast  iron,  new o .  65 

Cotton 0.75 

Charcoal 0.71 

Copper o .  03 

Glass o .  60 

Mortar  and  lime  mortar o. 74 

Paper 0.78 

Plaster  of  Paris o .  74 


Polished  sheet  iron 0.092 

Rusted  iron. o .  69 

Sawdust 0.72 

Sheet  iron 0.57 

Tin 0.045 

Water i .  07 

Wet  glass i .  09 

Wool 0.76 

Zinc ;  o .  049 

Wood o .  74 


To  explain  the  application  of  the  above  the  wall  given  in 
Fig.  97  will  be  investigated.  The  wall  is  composed  of  4  ins. 
of  sandstone,  18  ins.  of  brick  work,  a  2-in.  air  space,  8  ins. 
of  brick  and  i  in.  of  plaster.  Where  sections  of  the  wall  actually 


*.* 


*l 

'i 

I 

I 

V, 

l 

1 

II 

\  is; 

-18- 


FIG.  97.—  Wall  Section. 

come  in  contact,  there  is  no  surface  resistance  and  the  wall 
may  be  considered  as  solid  except  for  differences  in  values 
of  C  for  the  various  materials.  When  air  can  circulate  it  is 
not  considered  an  insulator  as  the  convection  currents  carry 
heat  from  the  warm  to  the  cold  side.  The  value  of  air  space 
is  in  the  surface  resistance.  To  find  a  the  various  values 
of  T  must  be  known;  now  T  is  given  by  the  following: 


'a  =  fa  —  t'z  ; 


These  quantities  vary  inversely  with  the  different  values  of 
a,  since 

d\  T\  =  d2  Ts  =  a'zT'z  =  #4  Jo. 


196  ELEMENTS  OF  REFRIGERATION 

As  the  quantities  a  do  not  differ  by  great  amounts  these 
various  values  of  T  are  considered  as  equal  quantities  in  com- 
puting a. 

T  may  then  be  found  from  the  equation 

-  •  •  -  \  ? 

T=i6.2  —  4.oo/. 
In  this  case  the  total  thickness  is  31  ins.  and 

r=i6.  2-4X^  =  6°  F.; 

12 


IO,OOO 

. 

03  =  02  =  0i  =  0.82  +0.74+ 


10,000 


as  =  1.59  =  02  = 
K= 


*    _|-  -i     ,     i    _|  _    i    _j_o.33  |    i-5  +Q-66  ,  0-083 

2.OI        1.58       1.58       1.58      0.87       0.46      0.46        0.46 

I 


0.497+0.633+0.633+0.633+0.379  +  3. 

I 


7.62 


=  0.131, 


The  resistance  of  air  channels  is  negligible  because  of  the 
convection  currents. 

For  a  floor  or  ceiling  as  shown  in  A,  Fig.  98,  the  method 
is  quite  the  same.  When  the  high  temperature  is  at  the 
top,  however,  there  is  no  circulation  in  the  air  space  between 
the  plaster  and  the  floor  and  the  air  acts  as  an  insulating 
material. 

When  the  high  temperature  is  below  or  if  an  air  space  is 
in  a  vertical  position,  the  circulation  of  the  air  transmiis  heat 
by  convection  and  the  air  does  not  act  as  an  insulating  material. 


HEAT  TRANSFER,  INSULATION 


197 


In  any  case,  however,  there  is  a  resistance  at  the  surface  between 
the  air  and  the  partition  due  to  the  drop  T. 

When  the  same  constant  K  does  not  hold  over  a  complete 
wall  or  floor  owing  to  a  change  in  the  construction  as  occurs 
at  studs  in  a  partition  or  joists  in  a  floor,  the  value  of  K  for  the 
whole  surface  is  found  thus: 


K(Fi  +F2)  (tt  -  to)  =  KiFi  (/i  -  to)  +K2F2(h  -  to) 

K  =  KiFi+K2F2  =  2, 

Fi+F2 


(33) 


1 

—  * 

1 

- 


FIG.  98. — Floor  Sections. 

In  most  cases  the  areas  F  have  a  common  dimension,  so  that 
the  areas  are  proportional  to  the  widths.  If  these  are  bi  and  b2 
there  results  (Fig.  98), 

Kibi+K2b2 


K  = 


bi+b2 


(34) 


The  mean  constant  is  not  usually  found  for  a  wall  in  terms  of 
glass  and  wall  coefficient,  as  these  are  kept  separate,  but  there 
is  no  reason  why  this  could  not  be  done,  as  happens  with 
the  coefficient  for  partitions  with  partition  studs  in  the  cases 
which  follow. 


198  ELEMENTS  OF  REFRIGERATION 

With  the  high  temperatures  above  the  air  acts  as  an  insu- 
lating substance  and  the  following  for  the  floor,  Fig.  98  : 


10,000 

at  joists, 


0.05 


1.57         12X0.06         8X12X0.46         1.57 

at  space  between  joists, 
Ka= 


12  3  +  _  5 


=0.027 


1.57    12X8X0.06    1.57    12X0.03    8X12X0.06    8X12X0.46    1.57 

Combined 

K_  3X0.05  +  13  XQ^7. 
16 

With  the  high  temperature  below  on  account  of  the  convection 
currents,  the  air  does  not  act  as  an  insulating  substance  and 
the  following  results: 


0=1.57; 

£,=0.05; 

K                          * 

-t^-a 

4     -       1-25 

5 

=0.22; 

1.57  '  12X0.06  '  8X12X0.46 


16 

This  method  may  be  used  for  various  walls  and  partitions. 
The  following  values  have  been  computed  by  the  author  and 
these  values  compared  with  those  given  by  Kinealy,  Riet- 
schel  and  others. 


HEAT  TRANSFER,  INSULATION  199 


Values  of  a 
For  brick  and  plaster  or  masonry. 

Outside  a  =  I.23+o.74+43Xl-23+3lXa74r 

10,000 

=  1.97+0.00757 

since  7  =  16.2—  4/. 

Inside  0  =  1.56+0.00577 

=  1.65— 0.023/. 

For  wood  and,  approximately,  paper,  cotton,  wool,  coal 
and  sawdust: 

Outside  0  =  1.97+0.00757  =  1.98. 

Inside  0  =  1.56+0.00577  =  1.57. 

For  glass: 
Outside  0  =  i  .83  +0.007  T 

/T  =  ti-to        0\ 
=  2'°7( =  35°j. 

Inside  with  motion : 

0  =  1.63+0.0067 
=  1.83(7  =  35). 

Inside  without  motion: 

0  =  1.42+0.0057; 

=  1-59(7  =  35). 
Inside  with  motion  and  wet  from  condensation: 

0  =  2.n+o.oo87 
=  2.39. 


200  ELEMENTS  OF  REFRIGERATION 

For  double  windows: 

Outside  0  =  1.95(7  =  1x70); 

Center  a  =  1.51. 

Inside,  dry  a  =  1.74. 

Pipe  Covering.  The  use  of  pipe  covering  to  prevent  the 
conduction  of  heat  from  steam  pipes  or  to  brine  pipes  or  vessels 
must  be  considered  in  this  chapter.  The  discussion  applies 
to  covering  on  all  circular  bodies.  The  constants  of  this 
chapter  may  be  used  in  this  case.  The  transmission  formula 
now  becomes 


For  flat  plates  of  insulating  material  the  expression  to  be 
used  is 


For  cork  £=0.022. 

For 

Q  =  heat  per  hour  in  B.t.u.; 
c  =  B.t.u.  per  hour  per  degree  for  i  ft.  thickness; 
TO  =  radius  outside  of  covering  in  feet  ; 
r\  =  radius  of  pipe  in  feet; 
L  =  length  of  pipe  in  feet; 
F  =  area  of  surface  in  square  feet;  ,  -,,.  . 

/  =  thickness  of  covering; 
to  =  temperature  outside  covering  deg.  F.  ; 
t\  =  temperature  inside  of  covering  deg.  F. 


HEAT  TRANSFER,  INSULATION 


201 


Mr.  L.  B.  McMillan  has  recently  given  values  for  c  for 
various  temperature  differences. 


VALUES  OF  C 


Kind  of  Covering. 

Temperature   Difference. 

25 

50 

75 

IOO 

150 

200 

300 

400 

Johns-Manville  asbestos  sponge. 
Nonpareil  high  pressure  

0.027 
0-033 
0.034 
0.036 
0.029 
0-035 
0.038 

0.028 
0.033 
0.034 
0.036 
0.030 
0-035 
0.038 

0.028 
0.033 
0.034 
0.036 
0.031 
0.035 
0.039 

0.029 
0.033 
0.034 
0.036 
0.032 
0.036 
0.040 

0.030 
0.034 
0-035 
0.037 
0.033 
0.037 
0.041 

0.031 
0.034 
0.035 
0.037 
0-035 
0.038 
0.043 

0.032 
0-035 
0.036 
0.037 
0.039 
0.041 
0.047 

0.036 
0.037 
0.038 
0.039 
0.044 
0.045 
0.054 

Gary  85%  magnesia 

Johns-Manville  magnesia  
Carey  carocel 

Johns-Manville  asbestocel  .  . 

Johns-Manville  aircell  

The  insulating  of  cold  storage  houses  is  accomplished  by 
the  use  of  wooden  walls  with  air  spaces  as  shown  in  Fig.  99, 
brick  walls  with  wooden  backing  as  shown  in  Fig.  100,  brick 
walls  with  air  spaces  as  shown  in  Fig.  101  and  brick  walls 
lined  with  some  non-conductor  as  shown  in  Fig.  102.  The 
main  purpose  in  using  these  is  to  increase  the  heat  resistance. 
The  older  storage  houses  were  of  wood  and  the  method  shown 
in  Fig.  99  gave  good  satisfaction.  The  use  of  paper  or  felt 
coated  with  some  substance  to  waterproof  it  keeps  the  saw- 
dust and  air  space  dry  as  well  as  making  the  wall  air  tight. 
Sawdust  or  mineral  wool  is  used  in  the  air  space  for  the  purpose 
of  preventing  air  circulation.  This  is  accomplished  in  air 
spaces  by  using  horizontal  strips  which  should  be  put  at  inter- 
vals between  them.  Fig.  100  shows  a  construction  recommended 
by  the  Frick  Company  for  warehouses.  At  times  cement, 
concrete  or  asphalt  is  put  on  wooden  floors  as  a  wearing  sur- 
face. Fig.  10 1  shows  the  brick  type  of  insulation  which  is 
valuable  although  expensive.  Where  space  is  valuable  some 
of  the  brick  may  be  replaced  by  cork  board  or  by  lith  as 
these  have  more  resistance.  The  type  shown  in  Fig.  102 
illustrates  such  a  protection.  Two  thicknesses  of  cork  board 
insulation  with  cement  between  are  used  to  get  the  neces- 
sary thickness,  as  these  boards  are  usually  made  no  greater 


202 


ELEMENTS  OF  REFRIGERATION 


than  3  ins.  in  thickness.  The  cement  is  usually  a  tar,  asphalt 
or  some  other  waterproof  binder.  The  surface  is  sometimes 
protected  with  a  cement  plaster  of  waterproof  properties. 


f 


FIG.  99. — Wooden  Wall  with  Sawdust  Fill.     (Elevation  above,  plan  below.) 

At  times  air  spaces  are  introduced  between  the  various 
thicknesses  of  boards  as  shown  in  Fig.  103,  and  in  some  cases 
the  outer  layer  may  be  replaced  by  two  of  lumber  with  paper 
between.  The  combination  used  depends  upon  the  peculiar!- 


Brick 


FIG.  ioo. — Brick  Lined  with  Wood. 


FIG.  ioi.— Brick  Wall  with  Air  Spaces        FIG.  102.— Wall  with  Lining  of 
and  Tile  Lining.  Cork  or  Lith. 

203 


204 


ELEMENTS  OF  REFRIGERATION 


ties  of  the  designer.     The  Union  Fibre  Co.  suggests  the  use 
of  their  linofelt  as  part  of  the  construction.     This  is  a  felt 


FIG.  103.— Brick  Wall  with  Wood 
Lining. 


FIG.  104.— Use  of  Lith 
and  Linofelt. 


Saw  Dusb 


i;.Saw  Dust 


FIG.  105. — Floor  Construction. 

made  of  flax  fiber  and  held  between  two  thicknesses  of  water- 
proof paper.     The  construction  is  shown  in  Fig.  104. 

Floors  are  insulated  as  shown  in    Fig.  100  and  Fig.  105, 
when  above  the  first  floor,  while  for  floors  on  the  ground,  Fig. 


HEAT  TRANSFER,  INSULATION 


205 


1 06  shows  the  method  used.     These  are  carefully  drained  and 
the  endeavor  is  made  to  keep  all  moisture  from  the  insulating 


8    S 


-.•- i.-.-y.': •  •  • '-  V,'  } : 'J  ffSt- 


Q 

Z 
3) 

o 
o: 
C5 

z 

O 

cr 
O 

3    § 


material.     Fig.  107  shows  a  form  of  wall  using  an  interlocking 
and  bonding  section. 


206 


ELEMENTS   OF  REFRIGERATION 


The  construction  used  in  making  grain  bins  consisting  of 
planks  2  X 10,  i  X 10  or  1X12  laid  on  the  flat  side,  has  been  used 
for  cold  storage  structure  by  some  builders  with  success. 
In  some  cases  such  walls  have  been  veneered  with  4  ins.  of 
brick.  All  of  the  preceding  drawings  are  given  to  show  some 
of  the  many  methods  used.  There  may  be  many  changes  sug- 
gested. The  general  method  for  finding  the  insulating  value 
of  a  wall  has  been  given  so  that  for  any  new  type  of  construc- 
tion the  insulating  value  may  be  determined  before  the  con- 


FIG.  107.— Special  Tile  Wall. 

struction  is  made,  in  order  to  ascertain  whether  or  not  addi- 
tional expense  would  be  justifiable. 

There  are  several  elements  entering  into  the  problem  of 
construction  of  a  cold  storage  warehouse.  Not  only  does 
the  original  cost  and  the  insulating  value  enter  into  the  prob- 
lem, but  also  the  cost  of  insurance  and  depreciation  must  be 
considered.  R.  E.  Spaulding  and  J.  H.  Nielson  have  pointed 
out  that  although  a  wood  ice-house  will  cost  $2.00  per  ton  of 
capacity,  and  a  fireproof  masonry  or  concrete  structure  cf  the 
same  insulating  power  will  cost  $2.50  per  ton  of  capacity,  the 
latter  costs  less  to  operate  because  the  depreciation  must  be 
figured  at  10%  for  the  wood,  and  at  3%  for  the  fireproof 


HEAT  TRANSFER,  INSULATION 


207 


structure,  building  insurance  $5.00  per  hundred  on  80%  of 
the  wooden  building  and  40  cents  on  80%  of  the  fireproof 
building  while  for  the  ice  the  insurance  is  $5.00  for  wood  and 
40  cents  for  concrete  per  100  tons  of  ice.  Considering  the 


FIG.  1 08. — Floor  Construction. 

interest  at  5%  with  the  above  items  the  yearly  cost  is  43  cents 
for  the  cheap  wooden  house,  and  21  cents  per  ton  in  the  fire- 
proof house. 

The  methods  of  this  chapter  have  been  used  to  compute 
the  values  for  various  types  of  insulation  and  the  results  are 


FIG.  .109. — Reinforced  Concrete  Roof  and  Ceiling. 

given  on  p.  211.  These  values  may  be  used,  if  desired,  to 
make  preliminary  calculations. 

Fig.  108  shows  a  construction  of  floors  using  arches  while 
Fig.  109  illustrates  the  method  of  hanging  a  ceiling  on  an 
inclined  reinforced  concrete  roof  to  form  an  air  space  or  to  give 
a  level  ceiling. 

The  construction  of  doors  is  an  important  question  in  the 


208  ELEMENTS  OF  REFRIGERATION 

operation  of  a  warehouse.  Not  only  must  these  be  non-con- 
ducting, but  they  should  be  air  tight,  because  the  temperature 
difference  might  set  up  a  strong  circulation  of  air  through  cracks, 
and  this  must  be  avoided. 

To  prevent  this,  leakage  doors  were  originally  made  as  shown 
in  Fig.  no.  The  numerous  corners  caused  troubles,  and  to 
do  away  with  them  other  arrangements  have  been  invented. 
Fig.  in  illustrates  a  section  through  the  Stevenson  door  in 
which  a  hemp  gasket  is  forced  into  place  by  the  closing  of  the 
door.  The  No  Equal  cold-storage  door  is  shown.  In  the  former 
the  soft  gasket  projects  ^from  the  door  flange  while  in  the  latter 
the  hair  felt  which  is  inclosed  in  a  ring  of  canvas  or  rubber 
is  placed  in  two  grooves  beneath  a  gasket  of  rubber  or  leather 
in  the  concave  quadrant  corner  of  the  door.  The  jamb  is 
rounded,  removing  all  sharp  corners  which  would  be  bruised 


FIG.  no. — Section  of  Early  Form  of  Door. 

and  which  would  prevent  proper  operation.  The  threshold  of 
the  doors  requires  special  treatment.  It  should  be  beveled 
off  to  the  floor  line.  The  packing  must  be  tight  here  to  make 
a  proper  fit. 

>  In  many  cases,  the  insulation  at  doors  is  made  more  perfect 
by  using  a  vestibule  before  the  main  door,  thus  requiring  two 
doors  to  be  opened  at  the  time  entrance  is  effected. 

The  insulation  of  ice  tanks  is  shown  in  Fig.  112.  The 
method  of  construction  and  computation  is  the  same  as  that 
used  above.  The  tank  may  rest  on  several  layers  of  cork 
board  or  on  wooden  sleepers  and  the  sides  may  be  insulated 
with  granulated  cork.  The  heat  loss  must  be  cut  down  to  a 
low  value. 

In  all  of  the  above  methods  of  insulation  care  must  be  taken 
to  prevent  moisture  from  entering  the  insulation,  as  the  value 
is  decreased  when  this  becomes  wet  and  the  wood  or  material 


HEAT  TRANSFER,  INSULATION 


209 


Stevenson  Door. 


.     , 

1  —  - 

:f: 

;:^:l 

i§^-f 

f    '                      1 

fe  1 

^) 

FIG.  in. — Arrangements  of  Doors. 


210 


ELEMENTS  OF  REFRIGERATION 


may  rot.     In  addition  the  insulating  material  should  be  of  such 
a  nature  that  vermin  cannot  breed  in  it. 

To  make  the  foundation  waterproof  the  cement  concrete 
may  be  treated  with  a  chemical,  but  if  this  concrete  cracks  a 
leak  occurs.  To  guard  against  this  the  concrete  may  be  coated 
with  a  waterproof  plaster,  which  is  less  likely  to  crack,  or  the 
foundation  may  be  coated  with  coal  tar  or  pitch  and  covered 


Wood 


Cork 


Cork 


FIG.  112. — Tank  Insulation. 

with  tarred  felt  and  burlap  covered  with  tar.  Care  must  be 
taken  to  waterproof  concrete,  as  water  is  drawn  up  by  capil- 
lary attraction  10  to  20  ft.  above  the  standing  water.  A  good 
method  of  waterproofing  is  to  use  bitumen  cement,  which  is 
strong  but  not  brittle,  applying  this  on  both  sides  of  each  of 
two  or  three  layers  of  felt.  For  floors  use  two  or  three  layers 
on  top  of  the  concrete  floor  and  then  apply  top  concrete.  For 
roofs,  a  layer  of  brick  may  be  put  on  top  of  felt  followed  by 
6  ins.  of  earth  with  grass. 

One  of  the  chief  points  i  to  consider  is  to  make  the  yearly 
cost  of  refrigeration  a  minimum.  This  includes  yearly  cost  for 
interest,  depreciation,  taxes  and  insurance  on  insulation,  with 
cost  of  storage  space  as  well  as  the  cost  of  refrigeration. 

The  values  of  K  for  different  types  of  insulation  have  been 
computed  and  are  given  as  follows: 


HEAT  TRANSFER,   INSULATION 

VALUES  OF  K 


211 


Total  Thickness  of  Brick  Masonry. 

Walls. 

4" 

8" 

12" 

16" 

2O" 

24" 

28" 

32" 

Solid  brick  

0.55 

o.  30 

0.31 

o.  25 

O.  21 

o  18 

o  16 

0.15 

Solid  brick  with  plaster  

0-51 

o-37 

0.29 

0.24 

O.  21 

0.18 

0.16 

0-15 

Brick  with  one  air  space  

o.  27 

O.  22 

0.19 

0.17 

0.15 

0.13 

0.12 

Brick  with  one  air  space  and  plaster  .... 

0.26 

O.22 

O.IQ 

0.17 

0.15 

0.13 

O.  12 

Brick  with  air  space,  4-in.  tile  and  plaster 

o.  14 

0.13 

O.  12 

O.II 

O.  IO 

0.09 

0.09 

Brick  with  3-in.  cork  and  plaster  

0.07 

0.07 

0.07 

O.O6 

0.06 

0.06 

0.06 

0.06 

Brick  with  2-in.  cork,  f-in.  cement,  2-in. 

cork,  |-in.  cement  

O.o6 

0.06 

0.05 

0.05 

0.05 

0.05 

0.05 

0.04 

Sawdust  Thickness. 

Walls. 

o" 

6" 

12" 

18" 

24" 

30' 

|  in.  wood,  paper,  |  in.  wood,  sawdust, 

f  in  wood  paper,  £  in.  wood      

o.  167 

0.044 

0.025 

0.018 

0.014 

O.OII 

Same  with  shavings  in  place  of  sawdust  .  .  . 

0.167 

0.062 

0.039 

0.028 

O.O22 

0.018 

|    in.  wood,   paper,  £  in.  wood,  sawdust, 

£  in.  wood,  paper,  |  in.  wood,  air,  |  in. 

wood,  paper,  £  in.  wood.     Fig.  99  

O.  IO2 

0.038 

0.023 

0.017 

0.013 

O.OII 

1  in.  wood,  paper,  £  in.  wood,  air,  |  in. 

wood,  paper,  3  ins.  cork,  %  in.  cement 

plaster 

O   OS7 

Same  with  6  ins.  cork       

«*  •  w  j  / 
0.036 

PARTITIONS 

|  in.  wood,  12  ins.  granulated  cork,  f  in.  wood #  =  0.024 

\  in.  plaster,  3  ins.  cork  boards,  4  ins.  granulated  cork, 

3  ins.  cork  board,  \  in.  plaster #  =  0.027 

Tile  partitions  plastered  single #  =  0.30  j 

Tile  partitions  plastered  double #  =  0.21 

FLOORS 

Fig.  108,    ist  figure #  =  0.022 

2d  figure #  =  0.062  heated  room  below 

#  =  o .  030  heated  room  above 
3d  figure K  =  0.060 


212 


ELEMENTS   OF  REFRIGERATION 


12  ins.  concrete,  2  to  3  ins.  cork  boards,  2  ins.  cement  ^  =  0.038 

Glass,  single  thickness K  =  i .  06 

Glass,  air,  glass #  =  0.41 

Glass,  air,  glass,  air,  glass . K  =  o.  26 

6  glass  and  5  air  layers K  =  o.  12 


FIG.  113.— Norton's  Method  of  Finding  K. 

The  value  of  K  for  cork  board  has  been  found  by  Prof. 
Norton  in  several  ways.     In  one  case  he  built  a  cubical  box 


HEAT  TRANSFER,  INSULATION  213 

of  the  cork  to  be  tested,  and  placed  a  piece  of  ice  within.  By 
weighing  the  amount  of  water  from  the  ice  the  heat  carried 
in,  was  found.  In  a  second  test  a  fan  was  placed  within  the 
box  and  electric  lamps  or  resistances  were  used  to  produce 
heat  and  by  circulating  the  air  the  temperature  was  made 
uniform  ;  then  by  measuring  the  energy  to  hold  the  box  at  some 
temperature  above  the  room  temperature,  the  heat  loss  per 
degree  was  found.  To  get  the  area  of  the  box  surface,  the  sur- 
face of  a  cube  at  the  mean  thickness  of  the  cork  was  computed. 
In  addition  to  this  the  heat  added  to  warm  oil  circulated  in  a 
tin  lining  on  the  inside  of  the  box  was  found  electrically 
and  reduced  to  B.t.u.  per  square  foot  per  twenty-four  hours. 
Norton  also  placed  a  wire  grid  between  two  thicknesses  of 
cork  board.  After  allowing  for  heat  losses  at  the  edge  by  keep- 
ing grid  at  a  certain  state  the  heat  loss  in  electrical  energy  per 
siuare  foot  per  degree  per  hour  was  found.  The  mean  value 
suggested  by  him  for  cork  is  ^  =  0.022.  These  methods  have 
been  used  by  German  experimenters  and  others  for  the  deter- 
mination of  K  for  various  substances. 

There  are  other  elements  entering  into  the  heat  supply 
of  refrigerating  plants.  Any  air  leakage  or  ventilating  supply 
must  be  cooled  off.  For  M  Ibs.  of  air  per  second,  the  heat 
per  hour  will  be: 


M  =  weight  of  air  per  second; 
cp  =  specific  heat  of  air  =  0.24; 
/o  =  temperature  outside  in  deg.  F.  ; 
ti  =  temperature  inside  in  deg.  F. 
p  =  pressure  in  pounds  per  square  inch; 
V  —  volume  per  minute  in  cubic  feet  at  p  Ibs.  pressure 

and  absolute  temperature  T\ 
£  =  53-35- 

The  heat  produced  by  persons  is  given  by  the  following 
results  by  Benedict  in  the  table  below: 


214  ELEMENTS.  OF  REFRIGERATION 

Adult  at  rest,  asleep  ..........  258  B.t.u.  per  hour 

sitting  ..........  396 

Adult  at  light  work  ...........  670 

Adult  at  moderate  work  .......  1150 

Adult  at  severe  work  ..........  1780 

For  children  an  allowance  of  300  B.t.u.  per  hour  may  be 
made. 

Heat  of  Machines  and  Lights: 

For  electric  lights  .......  i  watt-hour.  ...  3  .41  B.t.u. 

For  power  .............  i  K.W.-hr  .....  3410 

i  H.P.-hr  ......   2546 

For  gas  where  used  : 
i  cu.ft.  illuminating  gas  ...............     700  B.t.u. 

i  cu.ft.  natural  gas  ...............  .....   1000 

i  Welsbach  burner  uses  3  cu.ft.  of  gas  per  hour. 
i'  n?h-tail  burner  uses  5  cu.ft.  of  gas  per  hour 

If  substances  are  chilled  the  following  specific  heats  and 
constants  in  table  on  page  215  are  used. 

These  values  have  been  obtained  by  reference  to  various 
authors  and  are  collected  here  in  a  separate  table. 

See  Storage  Rate  Guide  for  rules  relating  to  charges  for 
storage,  rules  for  labor  charges,  liability,  etc. 

Having  the  amount  of  goods  put  in  a  storage  room  the  heat 
per  hour  to  cool  this  refrigeration  in  tons  is: 


Tons=  •  =  .     .     .     (35) 

199.2X60 


M  =  weight  of  goods  including  weight  of  container; 
c  =  specific  heat  of  substance  ; 
ta  =  temperature  of  outside  air  or  temperature  of    goods 

put  in  storage  ; 
tr  =  temperature  of  storeroom  or  temperature  of  goods 

after  storage; 

/<=heat  of  fusion  if  goods  are  frozen; 
h  =  hours  required  to  cool  goods; 
Q  =  B.t.u.  per  hour. 


HEAT  TRANSFER,  INSULATION 


215 


COLD  STORAGE  DATA 


Substance. 

Temp. 
Deg.  F 

Specific  Heat 

Latent 
Heat 
of  ' 
Fu- 
sion. 

Time 
of 
Stor- 
age. 

Cost 
of 
i  mo. 
Stor- 
age. 
Cents. 

Cost 
of 
Each 
Suc- 
cessive 
mo. 
Cents. 

Unit  of  Storage. 

Before 
Freez. 

After 
Freez. 

Apples  
Bananas  
Beans,  gree.i.  .  . 
Beans,  dried.  .  . 
Beef,  fresh  
Beef,  salt  
Beer 

30-35 
34-40 
36-40 
40-45 
30-38 
40-45 
30-36 
36-40 
15-20 
32-36 
34-36 
36-40 
40-45 
32-36 
34 
30 
40-45 
40-45 
30-31 

°-5  . 

35-40c 

35-40 
25-30 
25-30 
30-35 
15-20 
32-36 
32-40 
32-50 
32-36 
30-32 
32-36 
32-50 
30-34 
36-42 
32-36 
30-36 
30-32 
40-45 
34-38 
15-20 
36-40 
40-45 
36-40 
36-40 

36-40 

34-36 

40-45 

0.92 

0.91 
0.90 
0.70 
0.60 
0.90 
0.91 
0.60 
0.93 
0.92 
O.Q2 
0.84 
OT64> 
"""oT^rf^ 
0.90 

6  mo. 
3  mo. 

20 
10 

15 

itot 

* 

ia| 

i  to  * 

i 

20 
10 
IS 
12* 

IS 

25 
25 

5 
12* 

10 

i 

20 
12* 

Si.50  t 
$  .60  t 
$  .60  t 
1 
5 

10 
10 
12* 
i 
15 
10 
10 
25 

5 
5 
i 
* 

25 

i 

i 

* 

25 
12 

5 
35 

15 

10 
10 
itoi 

10 

i  to  * 

i 

15 

7i 

12 

12* 
10 

25 

20 

5 

12* 

7* 
i 
15 

12* 
0  2.00 

o    .75 
o     .75 
i 
4 
7* 
7* 

12* 
i 

15 
7i 

10 
25 
4 
4 
i 

25 
i 

i 
i 
* 
25 

12 

5 
35 

Barrel 

Bu.  basket 
loo  Ibs. 
lib. 
i  Ib. 
Half  barrel 
Quart 
i  Ib. 
100  Ibs. 
Box  or  crate 
*  bu.  basket 
loo  Ibs. 
loo  Ibs. 
Large  crate 
Barrel 
Per  cu.ft.  at  $5  val. 
100  Ibs. 
30  doz.  case,  55  Ibs 
i  Ib.  glazing 
loo  Ibs. 
loo  Ibs. 
per  season  each 
per  season  each 
per  season  i  cu.ft. 
i  Ib. 
10  Ib.  basket 
Box 
Box 
40  qt.  can 
lib. 
2  bu.  sacks 
Box  100  Ibs. 
Tub 
Sack 
*  bu.  basket 
*  bu.  basket 
i  Ib. 
i  Ib. 
Barrel  2*  bu. 
i  Ib. 
i  Ib. 
i  Ib. 
i  qt.  box. 
i  barrel 

i  bu.  crate 

i  melon 
i  barrel 

.... 

0.38 

0^84 
0.48 

90 

3  mo. 

Berries  
Butter  
Cabbage  
Cantaloupes.  .  . 
Cherries,  fresh  . 
Cherries,  drie  J. 
Cheese  
Celery  
Cider  

'  84 
129 

short 
5  mo. 

3  wks. 
4  mo 





Cigars  
Dates  
Eggs  
Fish,  fresh  
Fish,  dried  
Fruit,  dried.  .  .  . 
Furs,  coats.  .  .  . 
Furs,  rugs  
Furs,  uncured.  . 
Game  
Grapes  
Grape  fruit  .... 

0.84 
0.76 
o.7S 
0.58 
0.84 

0.40 
0.40 

100 
IOO 

6  mo. 
8  mo. 

.... 

0.80 
0.92 
0.92 
0.92 
0.90 
0.67 
0.91 
0.92 
0.84 

0.40 

105 

2  mo. 
3  mo. 
3  mo. 

5  mo. 
6  mo. 
3  mo. 

0.47 
0.8i 

0-44 

124 
114 

Milk 

Mutton  
Onions  
Oranges  
Oysters,  bulk  .  . 
Oysters,  shell  .  . 
Peaches  
Pears  
Pork,  fresh  .... 
Pork,  cured.  .  .  . 
Potatoes  
Poultry  
Sausage,  fresh.  . 
Sausage  ,  sm  oked 
Strawberries.  .  . 
Vegetables,  bbl. 

crate. 

Watermelons..  . 
Wines  

0.92 
0.92 
0.50 

0.80 
0.80 
0.70 
0.60 

0.92 
0.91 

0.91 
0.92 

O.c,0 

.... 

i  mo. 
2  mo. 
i  mo. 

6  mo. 
3  mo. 

short 
2  to  4 
weeks 
2  to  4 
weeks 

0.30 

0.42 
0.40 

90 

105 

102 

By  use   of   Eq.  (35)    the  amount  of  refrigeration  to  cool 
the  goods   and   freeze   them  may  be  computed.    It  is  well 


216  ELEMENTS  OF  REFRIGERATION 

to  note  that  the  time  required  to  do  this  is  an  important 
factor.  If  the  time  is  short  the  amount  of  refrigeration  is 
large.  This  amount  of  refrigeration  for  this  reason  may  be 
much  larger  than  that  required  to  care  for  the  heat  loss  from 
the  room. 


CHAPTER  VI 
COLD   STORAGE 

THE  purpose  of  cold  storage  is  to  prevent  the  development 
of  life  which  would  cause  decay  of  living  tissue;  it  is  also  used 
to  prevent  the  development  of  living  organisms.  It  is  used 
not  only  for  the  storage  of  foodstuffs,  but  for  the  storage  of 
furs,  trees,  flowers  and  other  articles  which  require  a  low 
temperature  for  their  proper  keeping. 

The  principal  application  of  cold  storage  is  to  the  storage 
of  food  products.  In  1905  W.  T.  Robinson  stated  that  there 
were  over  $200,000,000  worth  of  products  stored,  divided 
between  (a)  living  substances,  such  as  eggs  and  fruit,  requir- 
ing a  moderate  temperature  and  (b)  non-living,  as  meats, 
butter  and  cheese,  requiring  a  low  temperature.  In  1909 
the  value  of  goods  passing  through  cold  storage  amounted  to 
$2,585,000,000,  ranging  from  $25,000,000  in  fish  to  $1,500,000,- 
ooo  in  meats,  the  meat  annually  chilled  alone  amounting  to 
20,000,000,000  Ibs.  There  were  160,000,000  cubic  feet  of  stor- 
age space  exclusive  of  breweries,  packing  houses,  creameries 
and  stores. 

These  goods  are  stored  for  various  lengths  of  time.  Meats 
may  be  frozen  and  then  stored  for  a  long  time.  There  is 
some  improvement  in  quality  at  first  and  although  with  lengthy 
storage  there  is  no  deterioration  in  the  meat,  the  flavor  is  lost 
and  for  that  reason  long  holdings  are  not  good.  Poultry 
may  be  frozen  and  for  a  certain  length  of  time  there  is  an 
improvement  in  quality.  Eggs  may  be  held  for  long  periods 
and  except  for  a  loss  of  weight  there  is  no  ill  effect.  Cheese 
improves  as  it  ripens  in  cold  storage  but  after  ripening  there 
is  no  improvement.  Butter  suffers  slightly  in  taste  on  long 
storage.  Apples  and  pears  are  improved  by  holding,  as  certain 

217 


218  ELEMENTS   OF  REFRIGERATION 

chemical  changes  take  place,  while  strawberries  and  peaches 
lose  their  flavor  rapidly.  These  various  articles  require  special 
temperatures  for  their  storage  and  hence  there  must  be  special 
rooms  in  warehouses  for  each  article. 

The  value  of  cold  storage  is  to  equalize  the  supply  of  food- 
stuffs and  make  it  possible  to  have  certain  foods  during  the  whole 
year.  The  consumers  claim  that  goods  are  held  until  the  off- 
season and  then  exorbitant  prices  are  asked,  while  the  cold- 
storage  men  claim  that  prices  are  reduced  by  the  ample  supply 
which  exists  in  the  off-season.  Formerly  one  of  the  great 
evils  of  the  business  was  the  lengthy  storage  of  articles  for 
times  of  high  prices,  hence  laws  have  been  made  in  many  States 
to  correct  the  evils  of  cold  storage  of  foodstuffs  which  have 
hampered  the  business  and  brought  about  other  evils.  The 
United  States  Government  is  planning  a  national  cold-storage 
law  to  cover  interstate  business  and  business  in  the  District 
of  Columbia. 

The  cold-storage  bills  define  cold  storage  to  be  any  recepta- 
cle where  for  periods  longer  than  ten  days  food  products  are 
kept  at  40°  F.  and  under.  There  is  usually  a  time  limit  for 
most  substances;  this  varies  from  nine  to  twelve  months.  The 
materials  stored  must  have  the  dates  of  receipt  and  delivery 
by  the  warehouse  stamped  on  them  and  no  restorage  is  per- 
mitted in  some  States.  No  cold-storage  goods  with  dates 
erased  may  be  sold.  When  eggs  and  butter  are  stored  they 
must  be  sold  as  refrigerated  articles  and  signs  should  state 
this.  This  refers  to  eggs  after  thirty  days.  In  some  States 
there  are  fines  for  the  first  two  offenses  and  fine  and  imprison- 
ment for  the  third  offense.  An  important  feature  covered  by 
U.  S.  Senate  Bill  136  was  the  requirement  that  no  food  could 
be  placed  in  cold  storage  unless  in  a  sanitary  condition.  The 
condition  when  received  and  previous  history  of  an  article  to 
be  stored  is  as  important  as  the  storage.  The  Senate  bill 
prohibits  the  manipulation  of  cold  storage  goods  to  resemble 
fresh  goods  and  frozen  articles  must  be  sold  in  that  condition. 

An  investigation  by  the  U.  S.  Department  of  Agriculture 
showed  that  in  three  months  the  various  percentages  of  stored 


COLD   STORAGE  219 

goods  delivered  from  storage  in  certain  warehouses  expressed 
as  a  percentage  of  goods  received  at  the  beginning  of  the 
period  were  as  follows: 

Beef 71.2% 

Mutton 28.8 

Pork 95 . 2 

Poultry. , 75 . 7 

Butter 40 . 2 

Eggs.  .  ..14-3 

Fish 35.5 

And  in  seven  months  the  amounts  used  were : 

Beef 99     % 

Mutton 99 . 3 

Pork 99 . 9 

Poultry 96 .  i 

Butter 88.4 

Eggs 75.8 

Fish 64 . 9 

The  average  months  of  storage  were  as  follows : 

ist  Half  Ye~r         ad  Half  Year 
Months  Months 

Beef 2.6  1.8 

Mutton 4.8  3.0 

Pork 0.8  i.o 

Poultry 2.6  2.4 

Butter 4.5  4-° 

Eggs 6.1  1.7 

Fish 6.8  6.7 

This  investigation  shows  that  goods  do  not  remain  in  storage 
for  a  long  time. 

The  goods  stored  are  handled  in  special  ways  and  these  will 
now  be  discussed  together  with  certain  data  to  be  used  in 
designing  cold-storage  warehouses. 


220  ELEMENTS  OF  REFRIGERATION 

Eggs.  It  has  been  stated  that  of  the  3  billion  dozen 
eggs  produced  in  the  United  States  yearly,  240  million  dozen, 
or  one-twelfth,  are  put  into  cold  storage.  Eggs  are  usually 
placed  in  cases  containing  30  doz.  These  cases  weigh  about 
50  to  55  Ibs.  and  are  usually  stored  in  tiers  five  or  six  high 
with  slats  between  cases  to  give  a  chance  for  air  circulation 
and  the  removal  of  heat.  These  cases  are  12X13X25  ins. 
and  occupy  2\  cu.ft.  of  space.  The  eggs  lose  weight  on  storage, 
about  7%  being  lost  in  five  or  six  months.  If  the  air  in  the 
storeroom  is  too  dry  there  is  considerable  loss  of  weight,  while 
damp  air  will  cause  a  fungous  growth  on  the  eggs.  In  many 
cold-storage  warehouses  there  is  no  forced  circulation,  the  ice 
on  the  pipes  keeping  the  air  a  proper  humidity.  Should  the 
air  become  too  moist  it  may  be  dried  by  putting  calcium 
chloride  trays  on  top  of  the  refrigerating  coils  and  draining  off 
the  solution  formed.  This  salt  may  be  regained  by  evaporat- 
ing the  water.  80%  relative  humidity  has  been  found  to  give 
good  results. 

The  eggs  are  held  at  30  or  31°  F.  and  as  they  absorb  odors 
they  should  be  placed  in  rooms  containing  eggs  only.  They 
are  placed  in  storage  in  April,  May  and  June  and  are  usually 
kept  for  about  nine  months.  They  have  been  kept  for  twenty- 
three  months  and  except  for  a  shrinkage  of  25%  they  were 
not  affected  by  storage.  The  cost  of  this  storage  is  10  cents 
per  case  for  the  first  month  and  7^  cents  for  subsequent  months; 
40  to  45  cents  would  be  the  charge  for  the  season.  At  20  cents 
per  dozen  for  the  original  eggs  the  item  of  30  cents  for  the  case, 
30  cents  for  freight,  40  cents  for  storage,  25  cents  for  interest 
and  insurance,  and  40  cents  for  buying,  packing  and  grading 
makes  the  price  per  dozen  25.5  cents,  leaving  about  5  to  10 
cents  per  dozen  margin  for  the  owner,  wholesaler  and  retailer. 
January  is  considered  the  end  of  the  season.  The  eggs  should 
not  be  washed  when  put  in  storage,  as  this  spoils  the  appearance. 
At  times  they  are  candled  before  storage,  although  this  is  not 
done  regularly.  Candling  consists  of  holding  an  egg  in  front 
of  an  opening  in  a  metal  screen,  Fig.  114,  within  which  is  an 
electric  light  (originally  a  candle),  If  the  egg  is  not  good 


COLD   STORAGE 


221 


a  dark  center  due  to  the  thickening  of  the  yolk  will  be  noted. 
A  good  egg  will  appear  practically  uniform  in  texture,  the  light 
shining  through  the  egg.  Candlers  become  very  expert  and 
this  work  is  done  rapidly.  Candling  is  often  done  when  eggs 
are  taken  from  cold  storage.  Good  cracked  eggs  are  broken 
open  and  the  meat  placed  in  cans  holding  about  50  Ibs.,  which 
are  sealed  and  frozen.  These  are  used  by  bakers.  It  is  neces- 
sary to  use  these  soon  after  thawing. 

Uncracked  eggs  are  broken  and  canned  to  reduce  the  cost 


FIG.  114. — Candling  Box. 

of  shipment.  In  Sedalia,  Mo.,  a  large  plant  is  installed  for 
cracking  eggs.  Here  lof  millions  of  eggs  are  cracked  during 
a  season  under  highly  sanitary  conditions  to  prevent  con- 
tamination of  the  egg  meat.  The  eggs  are  broken  on  a 
knife  and  the  whites  are  separated  from  the  yolks,  the  latter 
being  well  mixed  before  sealing  the  can.  This  holds  30  Ibs. 
The  canned  cracked  eggs  are  frozen  and  shipped  to  bakers  for 
consumption.  It  happens  that  the  output  of  this  plant  is  used 
by  one  baker  alone. 

The  shipment  of  eggs  from  China  is  increasing.     The  U.  S. 


222  ELEMENTS   OF  REFRIGERATION 

Commerce  reports  from  Shanghai,  China,  state  that  the  ship- 
ment of  eggs  amounts  to  800  to  1000  tons  per  month,  i  ton 
being  40  cu.ft.  This  is  about  400,000  doz.  per  month. 

The  storerooms  for  eggs  and  for  all  other  storage  should  be 
kept  clean  and  should  be  whitewashed  about  once  a  year. 

The  whitewash  used  to  sweeten  rooms  can  be  made  with 
a  bushel  of  lime  slaked  in  boiling  water  with  a  peck  of  salt 
and  enough  water  to  make  a  thin  paste.  To  each  i2-qt.  pail 
of  this  add  a  handful  of  Portland  cement  and  a  teaspoonful 
of  ultramarine  blue  to  overcome,  a  yellow  discoloration.  To 
prevent  dust  on  concrete  floors,  a  solution  of  one  part  sodium 
silicate  (water  glass)  of  40°  Beaume  and  three  to  four  parts  of 
water  has  been  applied  to  a  dry  floor  after  washing. 

Butter.  This  is  held  at  33°  F.,  or  it  maybe  frozen  at  a 
temperature  of  15°.  It  is  considered  that  it  loses  flavor  with 
time  of  storage,  although  instances  are  given  where  the  buyer 
has  not  questioned  the  flavor  of  butter  held  for  two  years. 
It  is  better  to  store  it  in  bulk  than  in  small  packages.  The 
ordinary  butter  tub  weighs  50  to  60  Ibs.  and  occupies  about 
2  cu.ft.  -The  tub  must  be  sweet  and  clean  and  carefully  closed. 
It  is  sometimes  paraffined  on  the  inside  and  sometimes  lined 
with  parchment  paper.  If  the  air  is  damp  mould  will  form  on 
the  parchment.  Butter  will  absorb  odors  and  for  that  reason 
it  should  be  placed  alone  in  a  room.  The  amount  in  storage  in 
the  United  States  in  1909  probably  amounted  to  100,000,000 
Ibs.,  while  the  total  production  of  the  country  is  about  eighteen 
times  this  amount. 

The  temperature  does  not  seem  to  help  in  preserving  the 
flavor.  On  judging  cold  storage  butter  there  was  little  differ- 
ence in  the  total  points  of  butter  at  — 10°  F.  and  10°  F.,  but 
butter  at  10°  F.  was  much  better  than  butter  at  32°  F.  It 
depends  on  the  kind  of  butter  to  a  large  extent.  According 
to  Gray,  high  salt  content  and  hermetical  sealing  are  not 
advantageous  in  preserving  flavor.  A  common  method  of 
storage  is  to  chill  the  butter  at  first  to  o°  F.  and  then  allow 
the  temperature  to  rise  to  16  or  20°.  Oleomargarine  and 
such  products  may  be  held  at  about  20°  F. 


COLD  STORAGE  223 

The  temperature  carried  is  a  question  of  economy;    the 

cost  of  refrigeration  is  placed  against  the  saving  in  value  of 
flavor.  The  limit  of  time  of  storage  is  about  eleven  months. 
The  house  should  be  sweetened  with  whitewash  and  a  wash- 
ing of  roVo  bichloride  of  mercury  in  water  once  a  year. 

A  mixture  of  ice  and  salt  is  sometimes  used  for  the  cooling 
of  these  rooms.  Cooper  reports  a  butter-freezing  room  in 
Kentucky  where  1700  cu.it.  is  held  at  ioj°  F.  during  August 
by  the  use  of  507  Ibs.  of  ice  and  109  Ibs.  of  salt  per  day.  The 
egg  room  of  3560  cu.ft.  is  held  at  30°  F.  by  790  Ibs.  of  ice  and 
132  Ibs.  of  salt.  At  this  place  such  a  method  was  considered 
best  with  ice  at  $2.50  per  ton  and  salt  at  $7.00  per  ton. 

Cheese.  Cheese  weighs  60  Ibs.  to  the  box  and  occupies 
about  2  cu.ft.  It  is  stored  at  about  32°  F.,  although  36  to  40° 
is  used.  The  U.  S.  Government  tests  were  made  at  31  to  32°  F. 
Until  it  is  thoroughly  ripened  this  storage  improves  the  cheese. 
Beyond  that  time  it  is  not  improved.  The  cold  storage  will 
check  ripening  and  so  keep  the  cheese.  It  is  really  to  con- 
trol the  ripening  that  refrigeration  is  used.  To  prevent  loss 
of  weight  it  is  customary  to  coat  the  cheese  with  paraffin. 
It  should  not  be  frozen. 

Meat.  Meat  is  improved  by  exposure  to  cold  for  a  short 
time  if  kept  at  25  to  28°  F.,  but  after  about  three  weeks  it 
gradually  loses  its  flavor,  although  the  meat  is  preserved.  The 
fresh  meat  from  the  slaughter-house  is  placed  in  chilling  rooms 
and  it  is  cooled  to  the  temperature  of  the  main  storehouse. 
In  this  way  the  chill  room  is  equipped  with  excessive  coil- 
cooling  surface  so  as  to  remove  the  heat  at  the  proper  rate. 
Siebel  states  that  80  B.t.u.  of  refrigeration  per  twenty-four 
hours  is  required  for  every  cubic  foot  of  chill  room.  He 
states  that  i  ft.  of  2 -in.  direct-expansion  pipe  or  2  ft.  of  2 -in. 
brine  pipe  will  care  for  14  cu.ft.  of  chill  room.  If  the  meat 
is  to  be  frozen  for  storage  it  is  placed  in  a  room  at  10°  F.  and 
an  allowance  of  200  B.t.u.  per  twenty-four  hours  per  cubic  foot 
is  made  by  Siebel  and  one-half  the  previous  allowance  per  foot 
of  pipe  is  used.  This  freezing  is  resorted  to  for  shipment  and 
for  storage.  This  partially  destroys  the  flavor.  If  thawed 


224  ELEMENTS  OF  REFRIGERATION 

slowly  the  flavor  is  not  lost.  The  freezing  should  be  done 
slowly  and  meat  should  not  be  stored  in  such  large  piles  that 
the  heat  cannot  be  removed  from  the  center.  It  should  be 
held  so  that  heat  may  be  taken  from  all  parts.  If  this  is  too 
rapid,  the  outer  layer  freezes  before  the  inner  part,  and 
this  leads  to  certain  decay  at  the  center  of  the  meat.  The 
amount  of  refrigeration  may  be  computed  from  the  specific 
heats  and  heats  of  fusion  given  in  Chapter  V^when  the  weights 
are  known.  The  weight  will  vary,  but  the  following  averages 
may  be  used: 

Beef  (two  halves) 750  Ibs. 

Calves 90 

Sheep 75 

Hogs 250 

The  time  of  cold  storage  of  meat  may  be  at  least  six  months 
if  there  is  no  chance  of  thawing. 

Poultry.  The  storage  of  poultry  has  been  a  practice  for 
some  years.  The  poultry  is  frozen  and  kept  in  this  condition. 
Dr.  M.  E.  Pennington  has  investigated  the  matter  of  storage 
and  care  of  poultry  for  shipment  for  the  U.  S.  Government. 
She  points  out  that  the  preparation  of  the  fowl  for  storage  is 
as  important  as  storage  itself.  The  chickens  should  be  starved 
for  twenty-four  hours  before  killing  to  remove  the  putrid  matter 
in  the  intestines,  then  the  blood  should  be  removed  from  the 
tissues  after  killing  and  the  picking  should  be  done  without 
breaking  the  skin.  This  should  be  done  dry  and  not  after 
scalding  the  carcass.  The  carcass  and  especially  the  feet  should 
be  cleaned  and  prompt  storage  after  chilling  should  be  resorted 
to.  With  care  of  this  kind  the  poultry  is  good  after  three 
weeks  even  if  not  frozen.  The  chill  room  is  held  at  from  33 
to  38°  and  the  packing  at  from  30  to  32°.  Certain  State  laws 
allow  ten  months  storage  of  poultry.  This  is  accomplished 
by  freezing.  In  all  cases  the  entrails  are  undrawn  from  the 
carcass.  The  poultry  is  usually  placed  in  small  boxes  or  barrels. 
The  packages  should  be  small  so  that  air  can  reach  all  parts. 
The  boxes  should  not  be  piled  until  after  the  poultry  is  frozen. 


COLD  STORAGE  225 

Milk.  Milk,  if  free  from  the  germs  of  fermentation,  will  keep 
indefinitely,  but  this  condition  is  difficult  to  attain,  and  for  that 
reason  the  growth  of  the  germs  is  prevented  by  lowering  the  tem- 
perature. Of  course  the  pasteurizing  of  the  milk  by  warming 
it  to  a  temperature  of  180°  F.  will  kill  the  bacteria  and  not 
scorch  the  milk.  This  is  followed  by  rapid  cooling.  Milk 
should  be  cooled  as  soon  as  possible  after  being  drawn  from  the 
cow.  The  temperature  at  which  it  is  held  is  about  40°  F.,  for 
if  frozen  there  is  a  formation  or  separation  of  flocculent  par- 
ticles of  albumen  or  casein  compounds  which  do  not  redissolve 
readily  on  thawing.  Fat  globules  or  lumps  are  formed  also. 
The  cooling  of  the  milk  is  accomplished  in  special  block-tin 
coolers  arranged  so  that  they  may  be  thoroughly  cleaned.  The 
milk  passes  over  the  outside  and  the  refrigerant  on  the  inside. 
One  of  these  coolers  is  shown  in  Fig.  115.  The  Creamery 
Package  Co.  allows  20  sq.ft.  of  surface  in  these  coolers  per 
1000  Ibs.  of  cream  or  milk  per  hour,  making  the  cooler  of 
ij  or  2 -in.  copper  or  steel  tubes,  tinned  on  the  outside.  The 
trough  at  top  or  bottom  is  made  of  tinned  copper.  Other 
coolers  are  made  with  a  hollow  screw,  which  rotates  in  the  ripen- 
ing box,  while  the  screw  is  furnished  with  a  cooling  solution. 
By  having  a  hot  supply  in  the  screw  the  box  acts  as  a  pasteur- 
izer and  on  following  this  with  a  cool  solution  the  milk  is 
cooled  and  made  uniform  by  the  turning  of  the  screw. 

Cream.  In  the  storage  of  cream  a  low  temperature  is 
necessarily  combined  with  clean  storage  vessels.  This  cream  is 
used  largely  for  butter-making  and  in  many  of  the  eight  thou- 
sand creameries  of  the  United  States  refrigeration  is  not 
employed,  resulting  in  a  poorer  quality  of  butter,  as  cream  is 
often  held  for  some  time  by  farmers  before  shipment  to  the 
creamery  is  made.  The  separation  of  the  cream  is  carried  on 
by  the  de  Laval  separator  at  the  dairy  or  creamery  and  this 
may  be  done  best  at  about  160°  F.  The  cream  after  being 
cooled  to  50°  is  stored  and  finally  allowed  to  ripen  at  70°  F. 

Fish.  Fish  is  usually  frozen  and  coated  with  ice  before  ship- 
ment and  storage.  This  method  is  highly  developed  in  the 
Northwest,  1000  carloads  of  halibut  being  shipped  yearly  from 


226  ELEMENTS  OF  REFRIGERATION 


03 


til 


FlG.  115.— Spiral  Coil,  Disc  Coil  and  Tubular  Cooler  of  Creamery  Package  Co. 


COLD   STORAGE  227 

Vancouver.  The  fish  are  decapitated,  cleaned,  washed  and 
placed  in  sharp  freezers,  the  refrigerating  coils  acting  as  shelves. 
Certain  of  these  rooms  are  equipped  with  two  sets  of  eight 
shelves  made  up  of  i-in.  extra  heavy  pipe  37  ft.  long.  These 
pipes  are  supplied  with  liquid  ammonia  for  direct-expansion, 
and  by  keeping  liquid  in  each  of  them  the  system  is  flooded. 
Here  the  fish  remain  for  a  day  at  10  to  24°  F.  below  zero  and 
they  are  glazed  with  ice  after  freezing  by  dipping  them  in 
water.  This  ice  retains  the  fish  oil  and  keeps  the  flavor. 
After  this  operation  they  are  wrapped  in  parchment  paper  and 
boxed  for  shipment  at  10°  F. 

Oysters  are  held  in  cold  storage  at  35°  F.  for  some  time. 
After  opening,  the  oysters  may  be  placed  in  a  bucket  and  frozen 
solid.  This  is  not  advisable. 

Fruit.  Fruits  of  all  kinds  are  kept  in  cold  storage,  but  the 
time  in  certain  cases  should  not  be  long,  since  some  of  them 
lose  flavor. 

Apples  are  usually  stored  in  z\  bu.  barrels  weighing  about 
150  Ibs.  and  occupying  5  cu.ft.  of  space.  They  are  usually 
held  at  30  to  35°  F.  for  winter  apples  while  the  softer  summer 
apples  are  held  about  5°  above  these.  In  England  29  to  30°  F. 
has  been  used.  Apples  seem  to  improve  on  cold  storage; 
there  is  a  transformation  of  some  of  the  starch  into  sugar. 

Apples  have  been  kept  for  months  and  even  as  long  as  two 
years.  Care  must  be  exercised  in  picking  and  packing.  If 
carefully  picked  they  keep  for  a  considerable  time.  The  ship- 
ment abroad  is  very  extensive  and  the  loss  on  cold  storage 
apples  is  very  slight,  amounting  to  from  about  25  cents  to  some- 
thing over  a  dollar  per  barrel.  This  business  in  1910  amounted 
to  over  nine  hundred  thousand  barrels,  valued  at  mere  than 
two  million  dollars. 

Pears  aie  improved  by  storage  in  a  way  similar  to  that  for 
apples,  but  they  are  not  usually  kept  so  long.  The  temperature  is 
about  the  same  as  that  for  apples  or  a  little  higher — 30  to  36°  F. 
These  are  usually  placed  in  boxes  of  40  Ibs.  weight  when  full 
and  are  picked  in  an  under-ripe  condition.  Bushel  crates  are 
sometimes  used.  Closed  barrels  are  not  advisable,  as  the  heat 


228  ELEMENTS  OF  REFRIGERATION 

cannot  be  removed  from  the  center  fast  enough.  Wrappers 
of  paper  are  advisable  to  protect  the  fruit  from  bruises  and  to 
keep  the  color  bright. 

Peaches  are  kept  for  a  few  weeks  only  and  are  placed  in  boxes 
or  crates  weighing  about  20  Ibs.  They  lose  flavor  if  held  long. 
The  storage  is  for  the  purpose  of  transportation  and  to  lengthen 
the  season  for  selling.  They  are  held  at  from  32  to  36°  F. 
In  shipping  and  storing  these  the  boxes  are  placed  on  top  of 
each  other  about  five  boxes  high,  and  the  fruit  should  be  cooled 
slowly  and  warmed  slowly  to  prevent  sweating.  The  fruit 
should  be  carefully  picked  and  at  times  it  is  stored  slightly 
under-ripe. 

Strawberries  lose  their  flavor  on  storage  and  they  are  kept 
for  only  a  short  time.  They  are  held  at  40°  F.  to  prevent 
ripening.  Experiments  have  been  made  which  show  that  these 
and  other  berries  may  be  kept  for  four  weeks.  Huckleberries 
have  been  held  at  20°  F.  for  pie  making. 

Plums  may  be  kept  for  several  weeks  at  34°  F.  if  firm  and 
sound. 

Grapes.  These  may  be  shipped  from  the  West  with  success. 
They  are  held  at  various  temperatures.  Some  require  32°  F. 
while  with  others  34  to  36°  is  used.  They  should  be  dry  when 
stored.  They  may  be  held  from  one  to  two  months.  Seventy 
days  have  been  recorded  for  storage  in  redwood  sawdust. 

Oranges  and  lemons  are  important  items  in  the  commerce 
of  California.  This  business  amounted  yearly  in  1905  to  over 
$25,000,000  or  30,000  car  loads.  These  cars  hold  from  15,000 
to  30,000  Ibs.  of  fruit.  The  matter  of  storage  has  received  close 
attention  froir.  the  government  as  well  as  from  private  parties. 
Oranges  are  picked  at  convenient  times  from  February  to  May 
and  are  usually  shipped  in  crates  15X15X30  ins.,  weighing 
about  70  Ibs.  These  are  placed  on  end  in  storage  and  usually 
in  two  layers.  The  fruit  must  be  carefully  picked,  as  bruised 
fruit  decays.  They  should  be  held  in  shipment  at  32  to  50°  F., 
and  on  account  of  the  improper  care  the  loss  in  shipment  has 
amounted  to  over  one  million  dollars  per  season.  At  32°  F. 
they  may  be  stored  three  weeks  to  a  month,  but  oranges  are 


COLD  STORAGE  229 

uncertain  for  this  time.  At  times  the  storage  is  extended  to 
three  months.  They  give  off  large  amounts  of  gas  and  require 
ventilation  and  if  the  air  is  too  dry  shrinkage  occurs. 

Melons  may  be  held  for  several  weeks  at  35°  F.  They 
must  be  carefully  picked  and  selected  for  long  storage.  Usually 
the  storage  is  for  a  short  period. 

Bananas  are  usually  picked  green  and  are  allowed  to  ripen 
gradually,  the  amount  of  ventilation  determining  the  speed  of 
ripening.  At  34°  they  may  be  stored  for  some  time,  while  at 
40°  they  gradually  ripen.  At  32°  they  are  apt  to  turn  black. 

Vegetables.  Potatoes  are  held  at  35°  F.  in  bags  or  barrels 
and  should  be  so  stacked  that  air  may  reach  them.  This  must 
not  be  dry  air.  Potatoes  are  figured  at  60  Ibs.  to  the  bushel. 
If  in  barrels  there  will  be  5  cu.ft.  to  about  2\  bushels.  The 
room  should  be  dark. 

Tomatoes,  if  picked  when  just  starting  to  redden,  may  be 
kept  for  two  months.  They  are  usually  crated  after  wrapping 
in  tissue  paper.  They  are  held  at  40°. 

Onions  are  stored  at  about  34°  for  six  months.  These 
give  out  an  odor  and  should  be  kept  in  a  special  room.  They 
are  placed  in  bags  or  barrels. 

Celery  is  held  in  crates  of  about  140  Ibs.  These  crates 
are  about  24X24X30  ins.  Celery  is  held  at  about  34°  F.  for 
three  or  four  months.  The  seasons  for  production  in  different 
parts  of  the  United  States  make  it  possible  to  get  this  at  all 
times  of  the  year. 

Cabbages  are  held  at  35°  F.  These  are  stored  in  barrels 
or  crates.  Air  circulation  is  necessary. 

Tobacco  and  cigars  are  held  at  40  to  45°  F.  and  will  retain 
their  flavor  if  kept  in  one  condition.  This  low  temperature 
prevents  the  development  of  insect  life. 

Furs,  Rugs  and  Clothing.  The  matter  of  the  cold  storage 
of  goods  subject  to  moths  and  other  insects  received  attention 
during  the  last  decade  of  the  nineteenth  century.  In  a  paper 
by  Dr.  L.  O.  Howard  it  was  stated  that  insects  caused  a  loss  in 
cereals  of  one  hundred  million  dollars  per  year,  and  Mr.  A.  M. 
Reed  conceived  the  idea  of  preventing  a  similar  loss  from  insects 


230 


ELEMENTS  OF  REFRIGERATION 


acting  on  furs  and  woolen  goods  and  experimented  on  the  eggs 
of  the  moth  and  buffalo  beetle  and  found  that  50  or  55°  F. 
was  sufficient  to  prevent  the  hatching  and  40°  prevented  the 


a       a        a       a 

Temporary  Storage 


Office 


Elevator 


a      a        a      a 

Receiving  Room 


Platform. 


Upper  Floors 


Eirat  Floor 


Section 


FIG.  1 1 6. —Small  Store  House. 

passing  from  the  larval  state.  The  miller  and  the  beetle  were 
killed  at  32°  F.  and  in  the  center  of  rugs  they  were  killed  in 
several  weeks  at  temperatures  of  32  to  40°  F.  This  led  to  the 
establishment  of  cold  storage  for  such  articles  held  at  32°. 


COLD  STORAGE 


231 


Florists  hold  lily  of  the  valley  pips,  lily  bulbs,  feins,  smilax 
and  other  plants  or  bulbs  for  months  at  low  temperature. 
They  also  use  the  cold-storage  room  to  control  the  growth  of 
plants. 

The  construction  of  cold-storage  warehouses  will  vary 
with  the  peculiarities  of  the  designer  and  the  requirements  of 
the  ground  selected  for  the  plant.  In  general  there  is  a  receiv- 
ing room  near  a  railroad  track  and  a  truck  platform  as  well, 
close  to  the  office  for  the  receipt  and  delivery  of  goods.  In  some 
cases  there  is  only  a  railroad  platform,  as  goods  are  handled 


Upper 

Floors 

1st 

Floor 

2"Cork 

Cork  2 
Brick  24 

<-            —  > 

,12"Brick 
2  "Cork 

2"Cork 
<-24"  Brick 

Cork  2' 

2"Cork 

\ 

^n  levator 

>      ^^       / 

J!3 

\                / 

(                                    Receiving  Platform                                      j 

FIG.  117. — Plan  of  Large  Store  House. 

each  way  in  carload  lots.  The  receiving  room  is  sufficiently 
large  to  hold  several  transhipping  hand  trucks  and  is  connected 
by  elevators  to  the  various  floors.  In  small  houses  the  elevator 
shaft  could  pass  through  the  center  of  the  house  opening  into 
four  rooms  placed  around  it  on  each  floor.  The  separate 
rooms  are  required  to  give  the  necessary  number  of  rooms  for 
the  differing  foodstuffs  to  be  stored.  This  plan  is  shown 
in  Fig.  1 1 6.  In  this  way  the  elevator  serves  the  four  rooms. 
The  attic  under  the  roof  is  used  for  the  condensers  and  storage 
and  also  serves  as  a  heat  insulator.  The  cork  insulation  on 
outside  walls,  certain  inner  walls,  ceiling  of  first  floor  and  oi> 
the  upper  ceiling  is  shown  by  heavy  lines. 


232 


ELEMENTS  OF  REFRIGERATION 


For  extensive  plants,  as  those  built  in    cities,  the  rooms 
may  be  larger  and  extend  over  the  complete  space  of  one  floor. 


hr 


luster  Finish  \  Gutter 


1 

4  Solid  Cork  Partition  Walls 
PlasteredVinside  and  out     v 

*                \              V                 \        v 
rCement\Top  finiehV              \^_          N  v    ^ — 
2"Concre\e 
x  I"  Cork  Board 


Concrete  Floor       LI 
Construction 


1...I          Double  Pipe         |..r~ll 

fai  Ammonia  Condenser//^1 | 


FIG.  118. — Arctic  Cooling  Plant  for  Store. 

Such  a  plant  is  shown  in  Fig.  117.  The  elevators  in  this  plan 
serve  two  houses  or  two  rooms  of  one  house.  A  small  storage 
room  for  a  market  is  shown  in  Fig.  118  in  which  the  various 


COLD   STORAGE 


233 


details  may  be  seen  easily.  The  use  of  a  brine  tank  or  con- 
gealer  makes  it  possible  to  shut  down  the  machine  at  night 
after  freezing  the  brine,  this  frozen  brine  furnishing  the  re- 
frigeration during  that  time.  The  various  parts  of  the  plant 


may  be  traced  out.     The  congealer,  Fig.  119,  for  wall  coils, 
is  sometimes  used  in  larger  rooms. 

Figs.  120,  121  and  122  show  the  arrangement  of  pipes,  insu- 
lation room  and  machinery  for  small  plants.  In  Figs.  118  and 
122  the  air  circulation  may  be  followed. 


Oil  Charging 


COLD  STORAGE 


235 


236 


ELEMENTS  OF  REFRIGERATION 


The  various  arrangements  of  piping  are  shown  in  Fig.  123. 
In  Fig.  Aj  the  coil  is  carried  on  the  ceiling  while  in  B  it  is 
carried  on  the  walls.  When  the  coils  are  carried  on  the  ceil- 
ing, moisture  is  likely  to  drop  from  the  pipes  on  the  goods 
below/  and  then  the  ceiling  coils  are  placed  over  aisles  or  else 
they  are  placed  in  lofts  as  in  D,  E  and  F.  In  these  lofts  the 


FIG.  122. — Small  Store  House  of  Remington  Machine  Co. 

floor  is  placed  under  the  pipes  to  catch  the  drip  and  take  it  to 
a  gutter,  but  there  is  an  open  space  at  the  center  to  allow  the 
cold  air  to  fall,  while  side  partitions  near  the  center  or  at  the 
sides  near  the  walls  aid  in  circulation  of  air.  The  wall  coils 
are  better  in  most  cases,  although  there  is  danger  of  cooling 
the  goods  near  the  coils  too  much.  In  Figs.  C  and  E  there 
are  brine  tanks  or  congealers  used  in  the  rooms  and  the  cool- 
ing of  this  large  amount  of  brine  to  a  low  temperature  or  the 


COLD  STORAGE 


237 


freezing  of  the  brine  permits  the  compressor  to  be  shut  down. 
Figs.  A,  B  and  D  may  be  used  with  brine  or  direct  expansion 


E  F 

FIG.  123. — Arrangement  of  Piping  as  Shown  by  Creamery  Package  Co. 

of  ammonia.  C  and  E  are  for  direct  expansion.  For  inter- 
mittent operation  when  brine  is  to  be  circulated,  Fig.  F  is 
employed,  the  tank  supplying  the  refrigeration  on  shutting 


238 


ELEMENTS  OF  REFRIGERATION 


down  the  plant.     Such  an  arrangement  is  used  when  ammonia 
piping  is  objectionable. 

In  constructing  the  elevator  and  well  the  elevator  car  has 
a  ceiling  a?  well  as  a  floor  and  these  are  made  as  air  tight  as 
possible,  so  that  when  the  refrigerator  door  at  any  floor  is  open 
there  is  no  danger  of  air  circulation  from  the  warmer  air  out- 
side. The  floor  and  ceiling  of  the  car  have  rubber  or  felt  filling 


FIG.  124. — Elevator. 

strips,  closing  off  the  air  space  so  that  the  heat  loss  on  opening 
the  door  is  a  minimum.  Fig.  124  shows  this. 

Fig.  125  gives  a  section  through  a  storehouse  for  meats 
while  Fig.  126  illustrates  a  section  of  a  ship  containing  refriger- 
ated space.  The  arrangement  of  the  cooling  coils  for  cir- 
culation and  drip  is  to  be  noted  as  well  as  the  air  loft  under 
the  roof  as  in  Fig.  116. 

The  number  of  rooms  used  in  hotels  varies  with  the  hotel. 


COLD   STORAGE 


239 


240 


ELEMENTS   OF  REFRIGERATION 


COLD  STORAGE 


241 


Thus  in  the  Blackstone  Hotel  of  Chicago  the  following  cold- 
storage  rooms  are  found: 


Basement. 

Vegetable  box n'  s"Xio'  J'Xf 

Fruit  box 13'  g"X  10'  3"X7' 

Meat  box 14'  4"X8'  V'X?' 

Bouillon  box 7'  2"X8'  4/7X7' 

Game  box 5'  6"X8'  4"X7' 

Egg  box 4'  6"X4'  2"X7' 


Butter  box 

Milk  box 

Cheese  box 

Oyster  box 

Fish  box 

Fine  wines  box .  . 


.4'6"X3'2"X7' 
....9'Xs'2"X7' 
-5'4"X3'3"X7' 
i2'o"X6'8"X7' 
....6'X6'8"X7' 
.  .7'9"X4'7"X7' 


Ice-cream  box 10'  o"X  10'  o"X  10' 

Sharp  freezer  box,  5'  o"X  10'  o"X  10'  o" 
Draft  beer  box 9'  o"X9'  o"X6' 

Banquet  Hall. 

Refrigerator i4'X4'X9' 


Kitchen. 

Poultry  box s'Xs'Xs'  I0' 

Fish  box 9'X3'X3r  10' 

Lobster  box 5'X3'X3'  10" 

Bouillon  box 2'  8"X  2'  8"X  2'  10" 

Cold  plate  box i3/X3/4//X3/  i°" 

Cold  plate  box ii/3//X4/X3/  10" 

Cold  meat  box VX4/X9/ 

Sandwich  box 6'X3'X9' 

General  kitchen 9'Xi3'X9' 

Oyster  box i6'X4/X9/ 

Pantry. 6'X6'X9' 

Freezers  for  ices 6'X3/X7/ 

Fruit  and  salad  box 5'X3'X9' 

Milk  box 4/X3/X3/ 

Baker's  box S'XS'XS' 

Icecream n'  6"X3'  6"X3/ 

Short  order s'Xs'  4"Xs'  10" 

Cook's  box i6'X4/X9/ 


In  addition  to  the  above  there  are  some  boxes  on  the  dining- 
room  floor  and  the  club  floor. 

To  do  this  work  and  to  cool  the  dining  rooms  and  certain 
places  as  well  as  to  make  some  ice  requires  a  5o-ton  machine 
and  a  7 5 -ton  machine. 

In  Fig.  127  a  direct  expansion  CO2  plant  for  a  brewery  is 
shown.  Each  storehouse  is  cooled  by  large  direct-expansion 
coils.  In  the  air  loft  above  the  fermenting  tanks  is  noted 
a  sweet-water  cooler.  The  water  which  is  cooled  in  this  tank 
is  passed  through  coils  in  the  fermenting  vats  to  remove  the 
heat  of  fermentation  and  control  this  process.  The  large 
vats  are  used  for  proper  aging  before  storage  in  the  chip  casks 
on  the  lower  floor.  The  path  of  the  gas  from  the  two  compres- 
sors through  the  condenser  and  piping  and  the  construction 
of  the  walls  should  be  examined. 

The  refrigeration  for  storage  of  food  may  be  done  with 
natural  ice  and  salt  as  was  mentioned  in  Chapter  II.  In 
Minnesota  a  wholesale  and  retail  market  refrigerates  40,000 
cu.ft.  of  space  with  553  tons  of  ice  at  $1.65  per  ton  and  67  tons 
of  salt  at  $7.00  per  ton,  holding  the  room  at  15°  F. 


242 


ELEMENTS  OF  REFRIGERATION 


COLD  STORAGE 


The  walls  of  these  houses  and  the  floors  are  constructed 
in  various  ways.  Thus  at  the  Boston  Terminal  Refrigerating 
Co.  plant,  a  building  156  by  100  ft.  with  seven  floors  and  a 
ventilating  loft,  the  walls  were  made  of  4-in.  vitrified  water- 
proof brick,  8  ins.  of  hollow  tile  and  two  2 -in.  thicknesses  of 
Nonpareil  cork  held  in  place  by  asphalt  cement.  This  wall  does 
not  carry  any  of  the  floor  load.  The  building  is  of  reinforced 
concrete  and  the  only  floors  insulated  for  heat  are  the  base- 
ment floor,  third  floor,  and  eighth  floor.  These  floors  are 
insulated  with  two  thicknesses  of  2  in.  or  2-  and  3-in.  thick- 
nesses of  cork  board  with  an  asphalt  wearing  surface.  This 
construction  forms  a  fireproof  building.  A  suggestion  has  been 
made  to  use  two  4-in.  tiles  with  a  third  tile  8-ins.  from  the  outer 
ones  with  a  cork  filling  between  the  outer  wall  for  a  fireproof 
building.  This  wall  carries  no  weight.  The  columns  carrying 
the  weight  are  of  reinforced  concrete.  In  this  system  the  par- 
titions are  made  of  two  4-in.  tiles  with  a  6-  or  8-in.  cork  fill. 
The  floors  are  of  6  ins.  reinforced  concrete,  2  or  4  ins.  of  cork 
and  asphalt  on  top.  The  doors  are 
covered  with  iron. 

In  an  apple-storage  warehouse  the 
walls  were  made  of  2X6  hemlock 
boards  laid  flat,  as  are  used  in  grain 
elevators,  and  faced  on  one  side  with 
4  ins.  of  brick.  Fig.  128.  Such  a 
construction  should  give  good  results. 
The  installation  cares  for  15  cu.ft.  of 
space  with  i  lin.ft.  of  2  ins.  direct 
expansion. 

In  large  plants  the  insulation  is 
such  that  the  heat  loss  is  1.8  B.t.u. 
to  0.6  B.t.u.  per  square  foot  per 
hour  or  for  values  of  K  of  0.03  to 
o.oi. 


FIG.  128. — Grain  Bin  Construc- 
tion for  Apple  Storage. 


Any  of  the  forms  of  Chapter  VI  may  be  used  for  the  insula- 
tion and  for  any  form  of  construction  the  value  of  K  may  be 
computed  as  shown. 


244  ELEMENTS  OF  REFRIGERATION 

Partitions  between  rooms  may  be  made  of  two  2-in.  cork 
boards  faced  with  4-in.  tile  or  with  cement  plaster. 

The  temperature  of  the  rooms  should  receive  consider- 
able thought  in  determining  what  should  be  used.  The  highest 
possible  temperature  for  good  storage  should  be  used.  Some 
storage  men  claim  that  zero  rooms  cost  from  50  to  75%  more 
to  operate  than  rooms  at  30°  F.  The  proper  selection  may 
make  a  success  from  what  has  been  a  failure.  The  table  on 
p.  215  gives  the  temperatures  required  for  different  articles. 

After  the  temperature  is  fixed,  the  amount  of  insulation 
should  be  figured  so  as  to  make  the  annual  expense  a  minimum. 
The  annual  expense  is  made  up  of  interest,  depreciation,  taxes, 
insurance  on  insulation,  value  of  space  occupied  and  insurance 
on  the  stored  materials  and  the  cost  of  absorbing  the  heat 
leaking  through  the  insulation.  If  the  thickness  is  increased 
and  the  kind  of  insulation  improved,  the  first  items  will  increase, 
but  the  cost  of  absorption  will  be  decreased  and  if  the  sum  of 
these  is  decreased  then  the  improvement  pays.  If  the  sum 
is  increased  a  poorer  insulation  would  give  better  results,  the 
increase  due  to  the  cost  of  insulation  not  making  up  for  the 
saving  in  refrigeration.  By  plotting  these  costs  for  different 
thicknesses  the  best  thickness  may  be  found. 

In  estimating  these  items  the  charge  in  insurance  due  to 
various  constructions  must  be  considered.  Thus  in  frame 
buildings,  according  to  J.  H.  Stone,  the  insurance  is  i%  while 
in  fireproof  buildings  it  is  only  J%  and  ^%  for  semi-fireproof 
buildings.  This  refers  to  goods  as  well  as  buildings  and  this 
should  be  considered  in  fixing  the  cost.  The  depreciation  on 
insulation  is  taken  by  him  at  4%  in  good  construction  and 
at  8%  in  wooden  buildings.  The  cost  of  insulating  material 
is  given  by  Stone  as  27  cents  per  square  foot  for  2  B.t.u.  per 
square  foot  per  twenty-four  hours  per  degree  difference. 

The  cooling  is  accomplished  by  coils  or  by  air  circulation. 
The  coils,  as  shown  in  Fig.  123,  are  either  brine  coils  or  direct- 
expansion  coils.  In  some  plants  brine  is  thought  to  be  neces- 
sary. In  present-day  work  especially  with  welded  pipes 
ammonia  is  safe  and  is  used. 


COLD  STORAGE 


245 


The  direct-expansion  system  requires  less  difference  in  pres- 
sure between  suction  and  discharge  main,  giving  a  more  efficient 
plant.  The  brine  system,  however,  in  addition  to  the  question- 
able advantage  of  safety  in  case  of  rupture  does  possess  certain 


00000    00000       O O O~/P 


E  F 

FIG.  129. — Arrangements  of  Direct  and  Indirect  Refrigeration. 

advantages.  If  a  large  amount  of  brine  is  cooled  during  the  day 
this  may  be  used  when  the  compressor  is  shut  down  and,  more- 
over, the  cost  of  the  expensive  ammonia  to  fill  the  system  is 
eliminated.  To  increase  the  storage  capacity  it  is  even  pos- 
sible to  freeze  the  brine,  removing  about  150  B.t.u.  per  pound 


246  ELEMENTS  OF  REFRIGERATION 

of  brine.  These  advantages  are  worthy  of  consideration, 
although  the  lower  back  pressure  on  the  compressor  when 
brine  is  used  to  care  for  the  double  transfer  of  heat  makes 
the  advisability  of  its  use  a  matter  hard  to  determine. 

The  coils,  of  whatever  kind  they  may  be,  are  best  placed  on 
the  side  walls  near  the  ceiling,  as  ceiling  coils  are  apt  to  collect 
and  drop  moisture.  If  the  room  is  over  25  ft.  wide  a  ceiling 
coil  must  be  used  in  addition  to  the  side  coils.  This  should 
be  placed  over  aisles.  There  should  be  ample  coil  surface.  Of 
course  it  is  necessary  to  keep  certain  goods  at  the  proper  dis- 
tance from  side  coils  to  prevent  freezing.  The  use  of  cross 
aisles  and  the  arrangement  of  goods  in  tiers  to  aid  in  circu- 
lation of  the  air  of  the  room  are  advisable.  The  cross-sections 
of  rooms  are  shown  in  Fig.  129  in  which  the  circulation  is 
indicated.  The  use  of  the  aisles  to  separate  goods  of  differ- 
ent owners  is  advisable.  The  use  of  partitions  of  tin  around 
the  pipes  to  catch  drip  and  to  cause  a  definite  current  is  shown 
in  E  and  F. 

The  air  for  the  storage  room  should  be  cleaned  and  dried 
before  allowing  it  to  enter.  Ventilation  should  be  accomplished 
by  the  air  of  the  room  rather  than  by  outside  dirty  air.  In 
many  storehouses  such  as  the  4,300,000  cu.ft.  house  of  the 
Merchants'  Refrigerating  Co.  of  Jersey  City,  there  is  no  circula- 
tion provided.  The  circulation  is  all  brought  about  by  large 
pipe  coils  placed  over  the  aisles  and  not  at  one  place. 

In  the  indirect  system  of  cooling  by  air  circulation  air  is 
cooled  and  blown  into  the  room.  The  coils  may  be  placed  in 
ducts  in  ceiling  or  as  is  generally  the  case  they  may  be  placed  in  a 
large  space  called  a  bunker  room  and  the  air  blown  across  these 
is  carried  to  ducts  and  flues  leading  to  the  various  floors. 
The  distribution  of  air  in  the  storage  room  is  difficult.  In 
some  cases  it  is  distributed  through  numerous  small  holes  in 
the  ceiling  and  the  warmed  air  is  removed  through  holes  in 
the  floor.  In  this  way  an  even  distribution  over  the  whole 
room  is  obtained,  although  other  methods  are  used.  The  air 
may  be  recirculated  if  there  are  no  odors.  This  is  one  of 
the  objections  to  the  indirect  system.  Smoke  or  odors  from 


COLD  STORAGE 


247 


one  rooin  may  contaminate  the  stored  goods  in  another. 
129  illustrates  warehouse  rooms  using  forced-air  systems. 

The  bunker  room  is  shown  in  Fig.  130.  In  this,  brine  or 
a  volatile  liquid  is  passed  through  the  coils  and  abstracts  heat 
from  the  air,  which  is  blown  across  the  pipes.  The  moisture 


Dehydrator 


FIG.  130. — Bunker  Room. 


Fan 


removed  from  the  air  freezes  on  the  outside  of  the  pipes,  but 
by  circulating  brine  occasionally  over  the  pipes  this  frost  is 
removed  or  warm  brine  may  be  turned  in  when  the  air  is 
shut  off. 

In  some  houses  the  radiation  surface  is  increased  by  the 


FIG.  131. — Radiation  Discs. 

use  of  split  discs  added  to  the  outside  of  direct-expansion  pipes, 
Fig.  131.  These  are  not  used  often  at  present  although  in 
former  times  they  were  used  extensively  4 

The  air  is  driven  by  a  fan  blower.  Forms  of  blowers 
arc  shown  in  Fig.  132.  The  size  of  the  fan  and  the 
power  to  drive  the  fan  are  fixed  alter  the  sizes  of  ducts 


248 


ELEMENTS  OF  REFRIGERATION 


have  been  computed.  The  duct  sizes  are  fixed  by  the  allow- 
able velocities  of  the  air.  The  velocities  to  be  used  are  as 
follows : 

Main  ducts 1200  ft.  per  min.  =  20  ft.  per  sec. 

Branch  ducts 800          "  =13         " 

Register  faces 300  =   5 


Buffalo  Planoidal  Fan. 


Sturtevant  Multivane.  American  Sirocco. 

FIG.  132. — Fan  Blowers. 

The  quantity  of  air  is  fixed  by  finding  the  quantity  of  heat 
to  be  removed  and  the  allowable  rise  in  temperature  m  the 
air.  If  Q  is  the  heat  entering  the  room  per  hour,  tr  is  the 
temperature  of  the  room  and  fo  is  a  temperature  to  which  the 


COLD  STORAGE  249 

air  can  be  cooled  in  the  bunker  room,  the  volume  of  air  per 
hour  V  is  given  by 


=  Mv= 


,  —  tt) 


V  =  cubic  feet  of  air  per  hour  ; 

Q  =  heat  removed  per  hour  in  B.t.u.  figured  from  methods 

of  Chapter  V; 

U  =  temperature  at  outlet  from  bunker  in  deg.  F.  ; 
tr  =  temperature  of  room  in  deg.  F.; 
v  =  volume  of  i  Ib.  of  air 
=  12  cu.ft.  approximately. 

If  w  equals  the  velocity  in  feet  per  second  in  the  duct  or 
register  the  area  F  in  square  feet  is  given  by 


. 

3600^ 


(2) 


The  sizes  of  the  ducts  are  found  and  then  the  hydraulic 
radius  of  each  duct  is  computed.  This  is  equal  to  the  cross- 
section  of  the  duct  divided  by  the  perimeter.  If  b  and  d  are  the 
dimensions  of  the  duct  in  feet  and  RI  is  the  hydraulic  radius 
in  feet  the  following  are  true: 


-A-  (4) 


The  friction  loss  in  pressure  along  a  straight  pipe  of  L  ft. 
length  is  given  in  feet  of  air  pressure  by 


..     .    ....    .    .    .     (5) 


For  bends  of  radius  equal  to  2.6,  the  loss  is 


250  ELEMENTS  OF  REFRIGERATION 

In  grills  the  loss  is  given  by 


At  gradual  changes  of  section  there  is  no  loss. 
For  loss  in  the  bunkers  with  staggered  cooling  coils  the  loss 
of  head  may  be  taken  as 


for  each  coil  or  line  of  pipe  over  which  the  air  must  travel. 

If  now  in  any  line  the  sum  of  the  various  losses  is  taken, 
the  total  loss  may  be  found.  This  is  the  static  pressure  to  be 
produced  by  the  fan  and  in  some  fans  this  may  be  taken  as 

w2 
about  three  times  the  velocity  pressure,  —  .     The  sum  of  these 

2£ 

two  pressures  is  called  the  dynamic  pressure,  and  the  ratio  of 
this  to  the  static  pressure  is  usually  given  in  catalogs  of  fan 
makers.  The  static  pressure  varies  from  70  to  90%  of  the 
dynamic  pressure  in  various  forms.  The  dynamic  pressure  is 
the  one  listed  in  most  catalogs.  Having  the  dynamic  pressure 
in  feet  of  air  found  by  dividing  the  static  pressure  by  0.75,  this 
may  be  changed  to  ounces  per  square  inch  by  dividing  by  1  20 
for  air  at  70°  or  by  no  for  air  at  20°  F.  If  pressure  in  inches 
of  water  is  desired  this  pressure  in  ounces  per  square  inch  is 
multiplied  by  1.73. 

The  data  for  three  types  of  fan  are  given  in  the  table  on 
p.  251  for  the  points  of  best  efficiency: 

From  this  table  the  fan  must  be  picked  out  to  deliver  the 
desired  volume,  at  a  given  dynamic  pressure. 

Since  in  general  the  pressure  is  not  a  tabular  pressure,  the 
equivalent  volume  must  be  found  for  a  tabular  pressure. 
When  a  fan  is  run  at  the  same  point  of  its  efficiency  curve, 
the  pressure  varies  as  the  square  of  the  velocity  or  as  the  square 
of  the  number  of  revolutions;  the  quantity  of  discharge  varies 
as  the  velocity  or  number  of  revolutions  and  the  power  which 


COLD  STORAGE 


251 


FAN  DATA 


SIROCCO  FAN. 
Velocity  Press.  =0.288 
Dyn.  Press. 

BUFFALO  CONOIDAL  FAN. 

Velocity  Press.  =0.225 
Dyn.  Press. 

STURTEVANT  MULTIVANE 
FAN. 
Velocity  Press.  =0.10 
Dyn.  Press. 

a 

a 

Diam. 
of 
Fan 
Wheel. 

Dynamic 
Press. 

a 
1 

30 

Dynamic 
Press. 

S 

as 

Dynamic 
Press. 

ioz. 

I   OZ. 

ioz. 

2  OZ. 

ioz. 

I   OZ. 

00 

3 

Cu.ft. 
R.P.M. 
B.H.P. 

38 
2,290 
0.005 

77 
4-580 
0.037 

Cu.  ft. 
R.P.M. 
B.H.P. 

1,720 
632 
0.39 

3,435 
1,255 
3.  ii 

3 

Cu.ft. 
R.P.M. 
B.H.P. 

1,000 
502 

0.12 

2,000 
1,003 

I.O 

0 

4i 

Cu.ft. 
R.P.M. 
B.H.P. 

87 
15,24 
O.OII 

175 
4,58o 
0.084 

35 

Cu.ft. 
R.P.M. 
B.H.P. 

2,340 
545 
0.53 

4.675 
1,085 
4-23 

4 

Cu.ft. 
R.P.M. 
B.H.P. 

1,448 
4l8 

o.  19 

2,895 
835 

i.S 

6 

Cu.ft. 
R.P.M. 
B.H.P. 

155 
1,145 
o.  018 

310 
2,290 
0.147 

40 

Cu.ft. 
R.P.M. 
B.H.P. 

3,060 
482 
0.69 

6,100 
960 
5-52 

5 

Cu.ft. 
R.P.M. 
B.H.P. 

1.950 

359 
0.25 

3.900 
717 
2.0 

it 

3 

9 

Cu.ft. 
R.P.M. 
B.H.P. 

350 
762 
0.042 

700 
1,524 
0.333 

45 
50 

Cu.ft. 
R.P.M. 
B.H.P. 

3,890 
422 
0.88 

7.760 
845 
7-03 

6 

7 

Cu.ft. 
R.P.M. 
B.H.P. 

2,565 
314 
0.33 

5.130 
627 
2.6 

12 

Cu.ft. 
R.P.M. 
B.H.P. 

625 
572 
0.074 

1,250 
1,145 
0.588 

Cu.ft. 
R.P.M. 
B.H.P. 

4,78o 
378 
1.09 

9,560 
753 
8.67 

Cu.ft. 
R.P.M. 
B.H.P. 

4,000 
251 
o.S 

8,000 
501 
4.0 

3 

4 

18 

Cu.ft. 
R.P.M. 
B.H.P. 

1,410 
381 
0.^67 

2,820 
762 
i%33 

60 
70 
90 

Cu.ft. 
R.P.M. 
B.H.P. 

6,875 
3i8 
1.55 

13.650 
636 
12.38 

8 
9 
10 

Cu.ft. 
R.P.M. 
B.H.P. 

5,8oo 
218 
0.72 

1  1,  600 
435 
5-8 

24 

Cu.ft. 
R.P.M. 
B.H.P. 

2,500 

286 
0.296 

5,000 
572 
2.35 

Cu.ft 
R.P.M. 
B.H.P. 

9,450 

272 
2.14 

18,750 
542 
17.00 

Cu.ft. 
R.P.M. 
B.H.P. 

7,850 
1  80 
0.99 

15,700 
359 
7-9 

3 

30 

Cu.ft. 
R.P.M. 
B.H.P. 

3,910 
228 
0.460 

7,820 
456 
3-68 

Cu.ft. 
R.P.M. 
B.H.P. 

I5,6oo 

2IO 
3-54 

31,200 
419 
28.3 

Cu.ft. 
R.P.M. 
B.H.P. 

10,300 
157 
I  •  25 

20,600 
314 
10.  0 

6 
g 

36 

Cu.ft. 
R.P.M. 
B.H.P. 

5,650 
190 
0.655 

11,300 
381 
5-30 

no 
130 

Cu.ft. 
R.P.M. 
B.H.P. 

23,100 
172 
5.24 

45,700 
343 
41.4 

ii 

Cu.ft. 
R.P.M. 
B.H.P. 

12,925 
139 

1.64 

25,850 

278 

13.1 

48 

Cu.ft. 
R.P.M. 
B.H.P. 

10,000 

143 

1.18 

20,000 
286 
9-40 

Cu.ft. 
RJ>.M. 
B.H.P. 

32,400 
146 
7-34 

64,700 
291 
58.6 

12 

Cu.ft. 
R.P.M. 
B.H.P. 

16,000 
126 

2.  O2 

32,000 
251 

16.2 

38,800 
2.28 
19.5 

10 

60 

Cu.ft. 
R.P.M. 
B  H.P. 

15,650 
114 
1.84 

31,300 

228 
14-7 

150 

Cu.ft. 
R.P.M. 
B.H.P. 

43,ooo 
127 
9.80 

86,000 
253 
78.0 

13 

Cu.ft. 
R.P.M. 
B.H.P. 

19,400 
11^ 

2.44 

» 

72 

Cu.ft. 
R.P.M. 
B.H.P. 

22,600 
95 
2.66 

45,200 
190 

21  . 

170 

Cu.ft. 
R.P.M. 
B.H.P. 

55,500 

112 

12.55 

110,000 
235 
88.8 

I; 

Cu.ft. 
R.P.M. 
B.H.P. 

23,200 
105 
2.94 

46,400 
209 
23.5 

14 

8? 

Cu.ft. 
R.P.M. 
B.H.P. 

30,800 
81 
3.6i 

61,600 
163 
28.9 

190 

200 

Cu.ft. 
R.P.M. 
B.H.P. 

69,000 

IOO 

15.61 

137,800 
199 
124.8 

15 

Cu.ft. 
R.P.M. 
B.H.P. 

27,200 
97 
3-44 

54,400 
194 
27-50 

15 

90 

Cu.ft. 
R.P.M. 
B.H.P. 

35,250 
76 
4.14 

70,500 
152 
33-1 

Cu.ft. 
R.P.M. 
B.H.P. 

76,600 

94 
17-35 

152,500 
188 
138.0 

17 

Cu.ft. 
R.P.M. 
B.H.P. 

36,150 
84 
4-42 

72,300 
168 
35-4 

252  ELEMENTS   OF  REFRIGERATION 

varies  as  the  product  of  quantity  and  pressure  will  vary  as  the 
cube  of  the  number  of  revolutions.     Hence 


A7 
V  —  Ve  —  V  l 

~        ~ 


XV 


Ve  =  equivalent  volume  discharged  at  speed  Ne  revolutions 

per  minute ; 

Va  —  actual  volume  discharged  at  speed  Na\ 
Ne  =  revolutions  per  minute  to  give  total  dynamic  pressure 

Na  =  revolutions  to  give  pressure  Pa\ 
Pt  =  tabular  pressure ; 
Pa  =  actual  pressure. 

Having  Ve  the  fan  may  be  selected  and  then  Na  may   be 
found  to  give  the  proper  pressure  and  quantity. 

N'~NJJFI-     •••••••  •'•"••  •  (I0) 

The  power  to  drive  this  fan  is  given  by 

T7jL^;  («) 


HPa  =  actual  horse-power  to  drive  fan; 
HPt  =  tabular  horse-power  to  drive  fan. 

If  the  relation  between  static  pressure  and  velocity  pres- 
sure is  changed  from  that  used,  these  values  are  changed,  and 
although  the  tables  may  be  used  to  get  equivalent  quantities, 
there  is  little  use  in  giving  the  method  of  doing  this,  as  the  fan 
would  then  be  working  inefficiently. 

The  fan  and  its  power  to  be  used  are  now  known  and  the 
dimensions  may  be  found  in  the  tables  on  pp.  253  and  254. 


COLD   STORAGE 


FIG.  A. — Fan  Dimensions. 


DIMENSIONS  OF  SIROCCO  FAN  IN  INCHES 


Size. 

A 

B 

C 

D 

E 

F 

G 

H 

I 

J 

K 

N  • 

o 

P 

7 

28 

2Sl 

40 

42 

36 

3i* 

27* 

26^ 

23* 

28 

44 

8 

20 

3i* 

8 

32 

28f 

45* 

48 

40* 

36 

3i 

2Q 

25* 

32 

$c- 

9 

22 

35* 

9 

36 

3*1 

Si! 

54 

45* 

40 

34* 

34 

3o| 

36 

56 

9 

24 

40 

10 

40 

36 

57i 

60 

50^ 

44* 

38 

37 

33* 

40 

62 

10 

26 

44 

ii 

44 

39* 

62| 

66 

55 

48 

4i* 

39* 

36 

44 

68 

10 

28 

48 

12 

48 

43 

68| 

72 

$9* 

52* 

45 

45 

4i| 

48 

74 

II 

3° 

52 

13 

52 

46^ 

74* 

78 

64* 

57* 

49* 

48 

44i 

52 

80 

II 

32 

56 

14 

,5 

5oi 

80 

84 

6g 

sri 

5i 

52 

47! 

56 

86 

12 

34 

56 

15 

60 

54 

85f 

90 

73* 

64* 

54* 

53 

49* 

60 

92 

12 

36 

60 

DIMENSIONS  OF  BUFFALO  CONOIDAL  FAN  IN  INCHES 


Size. 

A 

B 

C 

D 

E 

F 

G 

H 

I 

K 

N 

0 

P 

30 

II 

ioi 

14! 

i6| 

i3f 

H 

12* 

12 

9* 

i7l 

3 

7 

isA 

35 

"i 

ia| 

*7i 

iQi 

is! 

16 

14* 

13 

io| 

20 

3 

8 

i7& 

40 

Hi 

14 

19! 

22f 

i7i 

18 

16 

14 

nf 

22| 

3 

8 

i8tf 

45 

i6i 

isi 

22f 

*5f 

2ci 

20 

i7l 

i5i 

I2| 

25f 

4 

9 

20^ 

50 

i8| 

17* 

24* 

28 

22 

22 

19* 

i6i 

i3i 

28^ 

4 

9 

22^ 

60 

22 

21 

29* 

33! 

26i 

26 

23 

19* 

16 

34i 

5 

ii 

26i 

70 

25* 

24* 

34* 

39* 

30* 

30 

26£ 

22 

18* 

39! 

6 

12 

30 

80 

29* 

28 

39* 

45i 

34! 

34* 

29i 

Mi 

2b| 

45* 

6 

14 

34! 

90 

33 

3i* 

44i 

Sof 

38| 

38* 

32i 

27i 

22f 

5i| 

7 

16 

38i 

no 

40| 

38* 

54 

61! 

47i 

47 

38! 

32i 

27* 

62^ 

8 

20 

46! 

130 

47! 

45* 

64 

73* 

ss! 

55 

4Sf 

37* 

32i 

73* 

9 

24 

54 

150 

55 

52* 

73f 

M 

64! 

64 

52| 

43 

37i 

84! 

ii 

28 

63i 

170 

62i 

59* 

83i 

951 

72! 

72 

S»l 

49 

42* 

96 

13 

32 

7ol 

190 

69f 

66$ 

93* 

107 

81 

82 

66f 

54 

46| 

107 

IS 

36 

82* 

200 

73* 

70 

98* 

II2f 

85i 

86 

69! 

56* 

48| 

II2f 

16 

38 

8si 

254 


ELEMENTS   OF  REFRIGERATION 


DIMENSIONS  OF  STURTEVANT  MULTIVANE  FAN 


Size 

A 

B 

C 

D 

E 

F 

G 

H 

I 

J 

K 

M 

N 

o 

p 

10 

40 

30* 

45 

52i 

40! 

37* 

26* 

36f 

38! 

32| 

48i 

32* 

10} 

20 

66| 

ii 

45 

34* 

50* 

584 

45* 

41* 

29* 

39« 

42* 

36f 

54* 

361 

12 

22 

73* 

12 

49* 

38* 

56* 

65l 

5i* 

46 

33 

43i 

46i 

4of 

60* 

40* 

12 

24 

81* 

13 

54* 

42 

6ii 

7if 

55l 

5i 

36 

46| 

5i 

44* 

66* 

44s 

id 

28 

8g* 

14 

59* 

45f 

67l 

7»f 

6o| 

55 

39 

49  f 

54* 

48f 

72* 

48} 

i*i 

32 

96 

iS 

64* 

40s 

73* 

84! 

65! 

60 

43 

54l 

59* 

52f 

78* 

52* 

14* 

36 

105 

16 

69* 

S3l 

781 

91* 

70 

64 

45 

58f 

64^ 

56! 

85 

56* 

I4| 

42 

112* 

i7 

74* 

57i 

84i 

97f 

74f 

68 

48 

62 

69! 

6o| 

9i 

60* 

i4i 

48 

I2Oj 

The  amount  of  coil  surface  used  in  the  rooms  of  a  store- 
house should  be  figured  by  the  usual  formula: 

Q  =  amount  of  heat  removed  per  hour  in  B.t.u.; 

F  =  area  of  surface  square  feet; 

K  =  constant  of  transmission  B.t.u.  per  square  foot   per 

hour  per  degree; 

=  5  to  10  for  brine  or  direct-expansion  coils  to  air; 
fc  =  mean  temperature  of  brine  or  ammonia,  deg.  F.; 
tr  =  temperature  of  room; 
/r-*c=io°toi5°F. 

The  quantity  Q  is  fixed  by  the  heat  entering  through  the 
walls  and  the  heat  gained  by  lights,  motors,  persons  and  goods 
stored.  The  heat  from  the  walls  and  other  causes  is  computed 
by  methods  of  Chapter  V.  Thejieat  given  up  by  articles  is 
given  by 


c  =  specific  heat  ; 

Ta  =  temperature  of  articles  before  storing; 
TV  =  room  temperature; 

//=  latent  heat  of  fusion; 
M  =  weight  in  pounds  ; 

h  =  hours  to  cool  and  freeze. 


COLD  STORAGE 


255 


Before  computing  this,  h  and  T  must  be  assumed  for  any 
substance,  h  is  fixed  by  the  designer,  and  the  temperature 
of  the  room  is  given  in  Chapter  V.  The  time  h  may  be  taken 
as  from  six  to  twenty-four  hours.  In  all  cases  it  is  better  to 
chill  slowly.  By  adding  the  various  heat  quantities  the  total 
is  found. 

On  account  of  the  ice  formation  over  the  pipe  the  value  of 
K  cannot  be  told  exactly,  and  for  that  reason  the  usual  method 
is  to  allow  a  number  of  cubic  feet  of  space  for  each  lineal  foot 
2-in.  pipe  for  direct  expansion  or  brine. 

In  some  cases  i  ft.  of  2-in.  brine  pipe  is  allowed  to  12  cu.ft. 
for  room  temperature  of  30°  F.  while  6  cu.ft.  only  is  used  for 
temperatures  of  from  5°  F.  to  10°  F. 

The  following  based  on  Levey's  tables  may  be  used  for 
2-in.  pipe  and  direct  expansion  in  rooms  with  good  insula- 
tion, say  1.5  to  2  B.t.u.  per  square  foot  per  twenty-four  hours. 


Cu.ft.  Per  Foot  of  2-in.  Pipe. 

Room 

Small  Rooms, 

Medium  Rooms, 

Large  Rooms. 

Limit  of  Length, 
Feet. 

Temp. 

1000  Cu.ft. 

5000  Cu.ft. 

10,000  Cu.ft. 

Brine. 

Dir.  Ex. 

Brine. 

Dir.  Ex. 

Brine. 

Dir.  Ex. 

Brine. 

Dir.  Ex. 

O 

I 

I 

2 

2 

3 

3 

IOO 

2OOO 

IO 

4 

5 

6 

8 

8 

12 

175 

2OOO 

20 

6 

8 

IO 

13 

13 

19 

225 

2000 

30 

8 

ii 

14 

17 

17 

25 

275 

2OOO 

36 

10 

14 

16 

2O 

20 

30 

300 

2000 

The  length  of  the  brine  coil  is  limited  by  the  amount  of  brine 
which  may  be  cooled  and  the  velocity  of  the  brine,  while  with 
direct  expansion  it  is  merely  a  matter  of  the  ammonia  which 
may  pass  through.  The  length  of  the  pipes  should  change  with 
various  diameters,  since  the  surface  varies  as  the  diameter,  while 
the  quantity  of  brine  or  ammonia  varies  as  the  square  of  the 
diameter.  The  brine  coils,  however,  are  not  varied  in  length, 
as  the  diameter  is  changed  while  the  direct  expansion-coils  vary 
as  the  diameter,  a  i-in.  coil  having  1000  ft.  as  its  limit  of  length. 
The  cubic  feet  of  space  cooled  per  foot  of  length  will  vary 
as  the  diameter  of  the  pipe. 


256  ELEMENTS  OF  REFRIGERATION 

The  allowances  made  by  Louis  M.  Schmidt  are  as  follows: 

DIRECT-EXPANSION  PIPING 
Freezing  and  brine  tanks.  ...   50  sq.ft.  per  ton  of  refrigeration. 

Brine  coolers  ...............    10 

Freezing  chambers  ..........  350  sq.ft.  per  1000  cu.ft. 

Storage  rooms  ..............  35 

BRINE  PIPING 
Freezing  chambers  ..........  500  sq.ft.  per  1000  cu.ft. 

Storage  rooms  ..............   50 

Bunker  rooms  .........  .....   20 

Skating  rinks  ...............   0.8  sq.ft.  per  sq.ft.  of  ice  surface. 

These  two  sets  of  tables  are  practical  rules  for  determining 
the  amount  of  surface.  The  better  method  is  to  use  the 
formulae  of  Chapter  V  and  from  them  compute  the  heat  lost 
and  the  pipe  surface  to  care  for  the  installation,  using  these 
tables  as  checks. 

E.  H.  Peterson  in  Ice  and  Refrigeration  for  November, 
1915,  gives  curves  showing  data  for  refrigeration  of  rooms 
of  storehouses.  For  "rooms  at  zero  degrees  his  curve  is  to  be 
given  by  the  following  equation: 


~  ,  .    ,  ,     ,  .        ,. 

Cubic  feet  per  ton  of  ref  ngeration  =  1000 


/cu.ft. 
1 


5000, 


Increase  this  by  80%  for  10°  F.,  150%  for  20°  F.,  250% 
for  30°  and  333%  for  40°. 

One  ton  will  care  for  3000  cu.ft.  on  an  average,  and  noo 
sq.ft.  of  insulated  surface. 

If  it  is  desired  to  find  F  for  the  coil  surface  in  a  bunker,  the 
quantity  K  will  depend  on  the  velocity  of  the  air  over  the  pipes. 
This  is  given  by 

K  =  2.2\/w  (for  wet  pipes  and  wet  vapor) 
K  =  i  +  1  .3  V_w  (for  dry  pipes  and  wet  vapor)  J 
w  =  velocity  of  air  in  feet  per  second; 
tr  is  then  equal  to  the  mean  temperature  of  the  air. 


COLD   STORAGE  257 

The  necessary  length  of  pipe  is  then  found  and  arranged 
as  in  Fig.  130,  which  shows  a  bunker  for  air  cooling. 

It  has  been  found  by  Sibley  that  ice  formation  on  the  pipe 
does  not  cut  down  the  heat  transfer,  but  aids  it.  An  "inch  of 
ice  in  a  brine  tank  coil  serves  to  increase  the  transfer  from  a 
ij-in.  pipe  to  about  four  times  its  previous  value,  while  2  ins. 
increases  it  twelve  times.  The  ordinary  allowance  of  120  to 
150  lin.ft.  cf  ij-in.  pipe  of  expansion  coil  in  a  brine  tank  per 
ton  of  capacity  is  decreased  by  him  to  40  ft.  when  ice  is  allowed 
to  form  on  the  pipes.  For  ice  making  this  ordinary  allow- 
ance is  doubled  to  from  240  to  300  lin.ft.  Sibley  states  that 
when  ice  can  form  around  the  expansion  coils  in  the  brine 
tank  the  rate  of  transfer  is  increased  as  stated  above. 

The  weight  of  ammonia  per  hour  for  a  room  or  plant  is  given 
by 

^=Ma.    .     .     .....     (15) 

^l-^4 

()  =  heat  in  B.t.u.  per  hour; 
M  a  =  weight  of  ammonia  per  hour; 
i\  =  heat  content  at  expansion  pressure  leaving  coils  ; 
24  =  heat  content  leaving  condenser. 

The  lines  carrying  liquid  ammonia  should  be  of  such  a 
size  that  the  velocity  of  the  liquid  is  not  over  4  ft.  per  second. 

The  return  lines  should  be  such  that  the  vapor  returning 
is  not  moving  faster  than  50  to  100  ft.  per  second. 

These  lines  may  be  figured  from  drop  in  pressure  using 
the  steam  formula: 


P=  pressure  drop  in  pounds  per  square  inch  in  length  L\ 
L  —  length  in  feet; 
D=  weight  of  i  cu.ft.; 
d  =  diameter  in  inches  ; 
M=  weight  in  pounds  per  minute. 

From  this  a  drop  may  be  assumed  and  d  found  or  with  a 
given  d,  P  may  be  found. 


258 


ELEMENTS  OF  REFRIGERATION 


Brine  is  formed  by  allowing  water  to  flow  over  calcium 
chloride  or  sodium  chloride.  This  is  best  done  by  having  a 
box  or  tank  into  which  the  brine  is  pumped  and  allowed  to 
flow  over  lumps  of  the  chloride,  and  after  dissolving  some  of  the 
salt  it  is  allowed  to  pass  out  through  the  bottom  of  the  tank. 
The  density  of  the  brine  is  fixed  by  the  temperature  at  which 
it. is  desired  to  carry  the  brine.  In  most  cases  of  closed  brine 
systems  it  is  necessary  to  keep  the  brine  from  freezing,  although 
in  congealing  tanks  it  is  desired,  that  the  brine  freeze.  The 
densities  and  temperatures  of  freezing  are  given  as  follows : 

FREEZING  TEMPERATURE  OF  SALT  SOLUTIONS 


Density  of  cal-  /  Sp.gr  

1.035 

1  .  062 

1.085 

1  .113 

I  .  122 

i  -I3S 

1-155 

cium  chloride  1  Deg.  Beaum6  at  64°.  . 

S-o 

8.6 

ii.  4 

14.7 

15-9 

17-9 

19.7 

Density  of  so-  j  Sp.gr  

1.  022 

1.044 

i  .067 

1.091 

I.  117 

i  .  142 

1.168 

dium  chloride  \  Deg.  Beaume'  at  64  ,°. 

3-0 

6.0 

9-0 

12.0 

15-2 

18.0 

20.9 

Temperature  of  freezing,  deg.  

28 

24 

20 

16 

12 

8 

4 

Density  of  cal-  /  Sp.gr  

i  .165 

1.174 

I.I86 

1.  197 

I  .  2O7 

i  .216 

cium  chloride  1  Deg.  Beaume"  at  64°.  . 

20.7 

21.7 

23-0 

24.1 

25-2 

26.1 

Density  of  so-  (  Sp.gr  

1.  193 

dium  chloride  \  Deg.  Beaum6  at  64°.  . 

23-5 

Temperature  of  freezing,  deg  

o 

-4 

-8 

—  12 

-16 

-20 

The  specific  heat  of  brine  varies  with  the  density  and  the 
specific  gravity.  The  latest  data  on  this  calcium  chloride 
brine  are  given  by  Dickinson,  Mueller,  and  George  in  the  bulle- 
tins of  the  Bureau  of  Standards,  U.  S.  Dept.  of  Interior,  Vol.  6, 
No.  3,  or  Reprint  No.  135.  In  this  the  specific  heat  of  brine 
at  c°  C.  is  given  by 

£  =  2.8821—  3.62729+1.779432;        (17) 

3  =  specific  heat  in  B.t.u.  per  pound  per  degree; 
D  =  specific  gravity  of  solution  at  o°  C.  compared  with 
water  at  max.  density. 

For  changes  in  temperature  from  o°  C.  the  value  of  8  is 
decreased  approximately  0.0008  for  each  degree  centigrade 
below  o°  C. 

The  specific  heat  of  sodium  chloride  is  taken  as  0.78  for 
1.2  sp.gr.,  0.86  for  i.i  sp.gr.,  0.94  for  1.05  and  0.98  for  1.02 


COLD   STORAGE  259 

sp.gr.     Having  the  amount  of  heat  per  hour  required  for  a  plant 
or  room,  the  amount  of  brine  required  per  hour  is  given  by 


(18) 


Q  =  heat  in  B.t.u.  per  hour; 
M  v  =  weight  of  brine  per  hour; 

3m  =  mean  specific  heat  at  temp.  - 

2 

to  =  temperature  of  brine  at  outlet  =  temp,  of  room—  10°  F.; 
ti  =  temperature  of  brine  at  inlet  =  fo  —  5°  to  8°. 

The  length  of  pipe  in  one  coil  is  such  that  this  heat  of  the 
brine  is  given  up  in  the  length.     Thus 


The  kind  of  brine  to  use  depends  on  the  engineer.  Some 
feel  that  calcium  chloride  will  not  corrode  nor  rust  the  iron  as  fast 
as  the  sodium  chloride;  neither  should  corrode  the  piping.  On 
account  of  the  impurities  in  the  salt,  brine  may  corrode  the  iron. 
If  there  is  any  acid  in  the  brine,  corrosion  may  occur.  If  there 
are  dissimilar  metals  in  the  system,  these  will  set  up  galvanic 
action  and  thus  corrosion.  Stray  electric  currents  may  also 
start  corrosion.  In  the  system  there  should  be  no  brass  pumps 
if  the  mains  are  of  iron  or  steel.  It  is  well  to  keep  the  brine 
alkaline  by  the  addition  of  lime  or  dilute  caustic  soda.  The 
calcium  chloride  permits  of  a  lower  temperature  of  brine  for  a 
given  concentration  and  for  that  reason  it  may  be  employed. 

The  brine  is  usually  forced  through  the  system  by  pumps 
of  the  direct-acting  type,  although  centrifugal  pumps  are 
employed  at  times.  The  direct  -acting  pumps  should  be  of 
such  a  displacement  that  they  will  deliver  their  full  capacity 
in  cubic  feet  at  45  cycles  per  minute. 

After  the  quantity  of  brine  required  per  hour  is  obtained 
by  (18),  the  size  of  pump  is  found  and  after  this  the  pipes  carry- 


269  ELEMENTS  OF  REFRIGERATION  j 

ing  the  brine  should  be  made  of  such  a  diameter  that  the 
velocity  will  be  4  ft.  per  second.  The  friction  loss  is  found 
by  using  the  equation: 


in  feet  =  S/    —  +2o.2w     —  .   ,  .    .     (20) 
Jd  2g  $  2g 

2  =  summation  sign  ; 
L  =  length  in  feet  of  any  size  pipe; 
d  =  diameter  in  feet  of  any  size  pipe  ; 
w  =  velocity  in  f  eetwper  second  ; 
n  =  number  of  elbows  of  any  size  pipe; 
L'  and  d'  =  dimensions  of  elbow  ; 

/=  coefficient  = 

Pumping  work  per  hour  =  Mt  XH.    .     .     (21) 

Cold-storage  warehouses  are  sometimes  operated  from  a 
central  refrigerating  plant.  These  central  stations  will  pay 
when  there  are  a  number  of  persons  needing  refrigeration  within 
a  limited  radius.  In  the  warehouse  districts  of  Boston,  New 
York,  Philadelphia,  Baltimore,  Norfolk,  St.  Louis,  Kansas 
City,  Denver  and  Los  Angeles  and  in  the  hotel  district  of 
Atlantic  City  central  stations  have  been  installed.  The  lengths 
of  mains  vary  from  i  to  17  miles  and  the  income  amounts  to 
about  $12,000  per  mile.  The  systems  may  be  of  the  brine 
system  or  the  direct-expansion  system.  In  each  case  there 
must  be  at  least  two  mains,  a  supply  and  a  return.  In  the  brine 
system  the  pipes  must  be  carefully  insulated,  as  the  brine  is 
at  low  temperature  and  about  2\  H.P.  is  required  by  the  brine 
pump  motor  per  ton  of  refrigeration  to  drive  the  brine  through 
the  main.  The  pipes  are  put  in  wooden  boxes  after  covering 
them  with  hair  felt  soaked  in  rosin  and  paraffin  oil.  The 
box  is  waterproofed.  The  arrangement  of  the  box  is  shown 
in  Fig.  133.  In  this  one  set  of  pipes  is  arranged  in  a  wooden  box 
while  in  the  other  a  split-tile  conduit  is  used.  The  pipe  is 
carried  on  supports  at  i2-ft.  intervals  for  2  -in.  pipe  and  over, 
while  for  i-in.  pipe  8-ft.  intervals  are  allowed.  At  certain 
points  the  pipe  line  is  anchored  and  on  each  side  of  this  anchor 


COLD  STORAGE 


261 


expansion  is  allowed  to  take  place.  Expansion  amounts  to 
0.08  in.  per  100  ft.  for  each  10°  of  temperature  change.  Expan- 
sion joints  are  placed  at  about  175  ft.  intervals  and  should  be 
of  the  pipe  bend  or  swinging  ell  type,  although  the  slip  joint 
as  shown  in  Fig.  134  is  used.  The  anchor  points  should  be 


FIG.  133. — Conduits  tor  Refrigerating  Pipes. 

points  at  which  branches  are  taken  off.    The  pipes  used  for 
brine  may  be  of  cast  or  wrought  iron. 

In  the  direct-expansion  system  there  is  no  need  of  insula- 
ting the  supply  main,  as  this  will  not  absorb  heat  from  any- 
thing as  cool  as  or  cooler  than  the  cooling  water,  since  the 
Ammonia  is  under  pressure.  The  return  main  should  be  in- 


262 


ELEMENTS   OF  REFRIGERATION 


sulated,  although  this  is  not  necessary  if  the  ammonia  vapor 
is  warmed  by  the  abstraction  of  heat  in  the  storehouse  to  at 
least  earth  temperature.  In  direct-expansion  installations  it 
is  customary  to  run  three  mains  with  cross-connections  at  man- 
holes and  warehouses.  One  pipe  is  used  as  the  pressure  main, 
one  as  the  return  and  a  third  as  a  vacuum  line  to  be  used  when 
it  is  desired  to  test  the  piping  in  buildings.  This  line  can  be 
used  to  charge  the  pipe  system  of  a  building  with  compressed  air 
for  testing  or  for  any  other  purpose.  The  joints  in  this  system 
should  be  welded,  as  leaks  are  very  expensive,  ammonia  being 
worth  about  25  cents  per  pound.  The  cost  of  ammonia  to 
charge  such  a  system  is  another  of  the  drawbacks.  The 


FIG.  134. — Expansion  Joint  for  Ammonia  Line. 

pressure  in  the  suction  main  would  be  fixed  by  the  coldest 
temperature  necessary  in  any  warehouse,  and  usually  a  drop 
of  15  Ibs.  is  allowed  in  the  main  to  drive  the  vapor.  The 
main  should  be  anchored  at  points  with  expansion  allowed 
for  by  bends  in  manholes. 

The  load  for  such  a  station  is  figured  by  allowing  i  ton 
for. about  3000  cu.ft.  for  spaces  up  to  40,000  cu.ft.  For  insu- 
lated areas  an  allowance  of  noo  sq.ft.  to  the  ton  will  care  for 
walls,  floor  and  ceiling.  The  temperature  on  the  three  hottest 
consecutive  days  is  used  in  computing  the  peak  load.  These 
may  be  found  by  getting  the  records  of  the  nearest  weather 
bureau  office. 

For  brine  lines  bell  and  spigot  cast-iron  pipe  has  been  used. 
Voorhees  has  installed  1500  ft.  of  lo-in.  pipe  of  this  kind  and  is 


COLD  STORAGE 


263 


supplying  two  warehouses  of  a  total  capacity  of  1,500,000 
cu.ft.  He  could  not  detect  a  rise  of  temperature  in  this  length 
on  thermometers  reading  2°  to  |" ',  showing  that  the  gain  of  heat 
in  the  duct  was  not  great. 

The  pipes  should  be  installed  perfectly  dry  and  kept  that 
way.  Paint  is  of  little  value  when  pipes  become  wet.  The 
best  thing  to  use  as  a  paint  is  some  form  of  bituminastic 
solution. 

AUTOMATIC  REFRIGERATION 

The  use  of  automatic  apparatus  by  which  the  tempera- 
ture of  rooms  is  kept  constant  is  one  of  the  recent  develop- 


Temperature 
Suction  Control 


FlG,  135.  —  Automatic  Refrigerating  Plant. 

ments  of  the  art.  In  this  method  an  electric  device  controls 
the  expansion  valve  and  the  pressure  in  the  expansion  coil 
regulates  the  motor  operating  the  compressor.  In  a  similar 
way  the  pressure  in  the  discharge  main  controls  the  water  supply 
to  the  condenser  and  on  the  pressure  reaching  a  limiting  high 
value  the  apparatus  is  shut  down,  thus  guarding  against  the 
failure  of  the  condensing  water  supply. 

The  claim  for  such  a  machine  is  that  the  amount  of  refrig- 


264  ELEMENTS  OF  REFRIGERATION 

eration  is  just  that  which  is  needed.  It  will  be  easily  under- 
stood that  when  a  room  is  cooled  off  below  the  required  tem- 
perature the  heat  flow  is  increased  and  more  work  than  that 
necessary  for  the  plant  is  done.  In  automatic  installations  a 
constant  temperature  may  be  maintained  and  one  no  lower  than 
that  required.  Of  course  this  also  prevents  the  temperature 
from  rising  above  the  desired  point,  and  although  this  would 
rarely  happen  in  a  well-operated  plant,  a  much  lower  tempera- 
ture may  be  carried  to  prevent  it. 

To  obviate  the  necessity  of  charging  refrigerator  cars  with 
ice,  compressor  plants  have  been  proposed.  For  instance 
in  Ice  and  Refrigeration  for  May,  1910,  there  is  a  description 
of  a  patented  system  in  which  a  small  compressor  is  placed  on 
the  car.  A  device  exhibited  in  Paris  in  1900  for  the  Russian 
railroads  is  worth  noting.  In  this  a  tank  of  liquid  ammonia 
was  placed  beneath  the  car  and  connected  to  an  expansion  coil 
in  the  car.  An  absorber  filled  with  weak  liquid  was  attached 
to  the  other  end  of  the  coil,  absorbing  the  vapor  and  main- 
taining a  low  pressure  in  the  system.  Enough  liquid  ammonia 
is  carried  for  a  given  run  and  at  the  end  of  this  run  the  liquid 
cylinder  and  the  absorber  are  removed  and  replaced  by  new 
ones.  The  liquor  can  then  be  boiled  and  the  ammonia  regained 
and  liquefied.  In  this  way  the  most  remote  points  of  the  car 
may  be  kept  cool. 

The  cold  storage  of  foodstuffs  on  refrigerator  cars  has  been 
recently  improved  by  precooling  the  car  and  its  contents  before 
shipment.  This  is  accomplished  by  forcing  cold  air  in  at  one 
end  of  the  car  and  drawing  out  warm  air  from  the  other. 
After  a  given  length  of  time  the  current  is  reversed  and  air  is 
drawn  from  the  end  into  which  it  was  forced,  and  withdrawn 
from  the  other  end.  In  this  way  a  large  amount  of  heat  can 
be  taken  from  the  car  before  ice  is  introduced. 

There  are  several  of  these  precooling  stations.  The  Santa 
Fe  System  has  one  at  San  Bernardino,  California,  and  the 
Southern  Pacific,  one  at  Roseville,  California.  At  these  stations 
twenty-four  to  thirty- two  cars  are  placed  in  connection  with 
ducts  which  are  covered  with  a  heat  insulator.  By  movable, 


COLD  STORAGE 


265 


266 


ELEMENTS  OF  REFRIGERATION 


telescopic  or  bellows  tubes  either  the 
main  door  or  one  of  the  ice  hatches  is 
connected  to  one  duct  and  both  ice 
hatches  or  the  other  ice  hatch  is  con- 
nected to  another  duct.  The  connection 
and  ducts  are  well  insulated.  Air  is  then 
blown  over  brine  coils  or  direct-expan- 
sion coils  in  a  bunker  room  and  is 
delivered  at  about  10°  F.  to  one  of  these 
ducts,  the  ice  forming  on  the  coils  from 
the  moisture  in  the  air  being  removed 
by  blowing  over  warm  air  when  the  cold 
brine  is  cut  off  or  by  the  use  of  calcium 
chloride  brine  which  trickles  over  the 
coil.  The  air  is  then  delivered  by  fans 
to  a  duct  and  then  by  means  of  tele- 
scopic tubes  to  the  car,  where  it  is 
warmed  20  or  25°  F.  and  is  drawn  out 
through  another  duct  by  the  suction 
of  other  fans.  The  pressure  of  the 
forcing  fan  is  from  ^  to  f  in.  of  water, 
while  an  equal  vacuum  is  produced"  by 
the  suction  fans  giving  atmospheric 
pressure  at  the  car  door.  This  is  neces- 
sary on  account  of  the  leaks  through  the 
car  walls.  The  air  currents  in  the  car 
are  arranged  to  reach  all  parts  and  by 
a  system  of  valves  the  air  currents  from 
the  ducts  are  reversed  in  the  cars.  The 
fruit  should  be  arranged  in  tiers  sep- 
arated for  ventilation.  In  some  cases 
the  air  discharged  into  the  car  is  shut  off 
while  the  suction  is  continued,  giving  a 
partial  vacuum  in  the  car.  On  admitting 
the  cold  supply  this  enters  the  parts 
of  low  pressure.  The  vacuum  also  tends 
to  draw  out  some  of  the  gas  from  the 


COLD   STORAGE  267 

fruit.  At  San  Bernardino  the  rate  of  6000  to  8000  cu.ft.  per 
minute  per  car  is  used  for  a  period  of  four  hours,  reducing  the  tem- 
perature of  car  and  goods  to  40°  F.  The  arrangement  of  the  car 
is  shown  in  Fig.  136.  Fig.  137  shows  the  general  arrangement 
of  the  plant,  which  represents  an  investment  of  about  $900,000. 

After  these  cars  are  reduced  to  40°,  or  the  temperature 
desired,  they  are  iced  at  the  station  and  then  shipped  east. 
The  car  may  then  be  sent  to  Chicago  without  further  icing 
and  the  fruit  will  be  in  far  better  condition  than  when  treated 
with  ice  in  the  ordinary  way.  The  cost  of  refrigeration  as 
ordinarily  run  with  ice  from  California  to  Chicago  is  $62.50 
per  car,  while  after  precooling  and  original  icing  by  the  shipper 
the  further  icing  is  reduced  to  $7.50  per  car.  The  cost  of 
precooling  is  $30.00  per  car  and  the  original  icing  is  $25.00. 

At  Springfield,  Mo.,  the  United  Fruit  Co.  cool  their  cars 
by  this  method,  lowering  the  temperature  26°  in  twenty-four 
hours.  In  this  way  they  may  be  held  cold,  the  rise  being 
2  or  3°  in  500  miles  of  travel. 

At  these  precooling  stations  ice  is  made  for  charging  cars, 
and  for  that  reason  the  plants  are  equipped  with  ice  storage 
rooms.  A  storage  plant  is  necessary  for  the  cooling  of  the  cars 
and  the  manufacture  of  ice.  The  plant  equipment  is  as  follows* 

Santa  Fe  at  San  Bernardino,  Cal. : 

Ice-making  capacity:  225  tons  per  day. 

Ice  storage:  30,000  tons  of  ice  (day  room  900  tons). 

Compressors :  two  3OO-ton  Vilter  refrigerating  machines. 

Cars  at  one  setting:  32. 

Bunker  rooms:  44  ft.  6  ins.  by  48  ft.  by  9.3  ins.,  and  8  ft. 

9  ins. 
Fans:  eight  i2o-in.  Sirocco  fans,  65,000  cu.ft.  per  minute 

each  at  f  in. 
Insulation:  3 -in.  cork  on  concrete. 

Pacific  Fruit  Express  Co.,  Roseville,  Cal.  (S.  Pac.  Co.); 
Ice-making  capacity:  250  tons  per  day. 
Ice  storage:  20,000  tons  (112  by  115  by  32  ft.  and  75  by 

115  by  32  ft). 


268  ELEMENTS  OF  REFRIGERATION 

Cars  at  one  setting:  24. 

Bunker  rooms:  80  by  26  by  9  ft.  and  8  ft.  high. 
Compressors:  two  25o-ton  York  compressors. 
Insulation   ice   house:    concrete   walls   with   3 -in.    lith. 

Air  duct  i-in.  boards:  |-in.  asphalt,  i-in.  boards,  3j-in. 

granulated  cork,  i-in.  boards. 
Fans:  four  fans 85  in.  diameter,  27!  in.  wide,  44,500  cu.ft. 

per  min.  at  380  R.P.M.     Pressure  3  oz. 

That  this  is  not  an  untried  invention  is  shown  by  the  fact 
that  over  2  2 ,000  cars  have  been  precooled  at  the  Santa  Fe  plant 
alone  during  a  period  of  about  five  years. 


CHAPTERJVII 

ICE    MAKING 

In  making  ice  two  methods  have  been  used  for  a  number 
of  years.  In  one,  distilled  water  is  placed  in  cans  and  these 
cans  are  surrounded  by  brine,  liquid  ammonia,  or  cold  air, 
which  removes  heat  from  the  water  and  causes  it  to  freeze. 
In  the  other,  water  taken  from  a  stream  or  other  supply  (known 
therefore  as  raw  water)  is  placed  in  a  large  tank  which  con- 
tains a  number  of  coils  of  pipe  for  vaporizing  ammonia  or  cir- 
culating brine.  This  removes  heat  from  the  water  until 
gradually  a  plate  of  ice  is  formed  on  each  face  of  the  coil. 
If  a  large  tank,  20  ft.  wide  by  60  ft.  long  by  8  ft.  deep,  contain 
20  coils,  40  plates  of  ice  could  form.  The  first  method  is 
known  as  the  can  system;  the  second  as  the  plate  system. 

To  study  the  peculiar  details  of  these  systems  two  general 
plans  will  be  examined,  after  which  the  details  of  construction 
and  operation  will  be  considered. 

Figs.  138  and  139  are  the  plan  and  elevation  of  a  25-ton 
standard  can  system  of  the  York  Mfg.  Co.  In  the  plan  view, 
Fig.  138,  the  compressed  ammonia  is  delivered  from  the  com- 
pressor to  a  double-pipe  condenser,  passing  through  a  separator 
before  entering  the  condenser.  From  this  point  the  liquid 
ammonia  is  carried  to  an  ammonia  receiver  shown  dotted  and 
seen  in  Fig.  140,  and  it  is  then  taken  to  a  liquid  line  on  top 
of  the  brine  tank  at  A,  Fig.  139.  From  the  liquid  line  it  passes 
through  expansion  valves  and  enters  the  expansion  coils  of  i  J-in. 
pipe  shown  in  the  longitudinal  section,  Fig.  139.  The  liquid 
enters  at  the  top  of  the  coil  and  flows  down  to  the  bottom, 
abstracting  heat  from  the  brine.  From  Fig.  140  it  will  be 
seen  that  there  is  a  coil  between  each  two  rows  of  cans.  The 
manifold  or  pipe  line  A  leading  the  liquid  to  the  coils  is  carried 

269 


270 


ELEMENTS  OF  REFRIGERATION 


ICE  MAKING 


271 


272 


ELEMENTS  OF  REFRIGERATION 


in  a  box  filled  with  cork,  as  seen  in  Fig.  139,  to  prevent  the 
abstraction  of  heat  from  the  room. after  leaving  the  expansion 


r    n 


FIG.   140. — Cross  Sections  of  25-ton  Ice  Plant.     York  Mfg.  Co. 

valve.  The  cans  are  30olb.  cans,  and  the  tank,  which  is  49  ft. 
9  ins.  by  21  ft.  by  about  5  ft.,  contains  352  cans,  or  fourteen 
3oo-lb.  cans  per  ton  of  capacity  per  twenty-four  hours.  The 


ICE  MAKING 


273 


cans  are  nj"  by  22\"  by  44".  The  brine-freezing  tank  is 
made  of  J-in.  steel  and  is  well  insulated  on  the  sides.  As 
shown  in  Fig.  141  the  brine  is  given  a  circulation  by  means  of 
a  propeller  blade  driven  by  a  motor  or  belt  from  an  engine. 
This  propeller  is  placed  on  one  side  of  the  end  of  the  tank 
and  by  running  a  vertical  partition  longitudinally  along  the 


FIG.  141. — Plan  of  De  la  Vergne  Freezing  Tank  with  Brine  Agitator. 

center  of  the  tank  to  within  2  ft.  of  each  end  a  channel  is  made 
to  cause  a  definite  circulation. 

The  vapors  formed  in  the  coils  are  collected  in  a  return  or 
gas  header  and  are  taken  to  the  suction  of  the  compressor. 
This  line,  Figs.  138  and  140,  is  carried  through  a  storage 
water  tank  so  as  to  remove  heat  from  the  distilled  water  which 
is  to  be  placed  in  the  cans.  This  completes  the  passage  of  the 
ammonia  and  the  compressor  delivers  the  ammonia  again 


274 


ELEMENTS   OF  REFRIGERATION 


to  the  condenser.  The  water  from  the  storage  tank  is  taken 
to  a  point  on  the  outside  wall  of  the  center  of  the  freezing 
tank  length  and  then  discharged  by  a  hose  into  cans  which 
have  just  been  emptied.  An  automatic  device  shown  in 
Fig.  142  cuts  off  the  water  supply  when  the  tank  fills.  These 

fillers  are  of  various  forms,  dif- 
fering in  detail.  The  K-C  Filler 
shown  in  Fig.  142  has  a  ball  at 
the  top  of  the  discharge  pipe,  the 
raising  of  which  closes  the  valve 
controlling  the  flow  of  water. 
This  is  lifted  by  the  water  as  it 
fills  the  can. 

When  the  water  is  frozen 
the  wall  of  ice  grows  from  the 
surfaces  of  the  can  and  gradually 
forms  a  core  at  the  center.  All 
of  the  impurities  in  the  water 
are  forced  toward  this  point,  as 
the  ice  first  forming  is  clear,  and 
if  the  water  is  dirty  or  contains 
scum  an  opaque  core  is  found 
at  .the  center.  Hence  the  water 
in  the  early  methods  was  dis- 
tilled and  boiled  to  prevent  the 
formation  of  this  core.  For  this 
reason  the  exhaust  steam  was 
condensed  and  used.  In  the 
plant  shown,  Figs.  139  and  140, 
the  exhaust  from  the  engine  is 
carried  through  a  grease  separator  to  a  condenser  placed  on 
the  roof  of  the  boiler  house.  From  here  the  condensed  steam 
is  carried  to  a  reboiler.  In  this  the  water  is  brought  to  a 
boiling  temperature  by  a  steam  coil  and  the  oil  and  other  im- 
purities remaining  in  the  condensed  steam  as  well  as  air  are 
forced  out. 

This  reboiler  is  placed  in  the  monitor  of  the  roof.     The  water 


FIG.  142.— K.  C.  Can  Filler. 


ICE  MAKING 


275 


-0  00  W'AV  W»I  SlWJttWJJi 


276 


ELEMENTS  OF  REFRIGERATION 


is  then  taken  through  a  cooling  coil  and  finally  passed  through 
several  filters  for  cleaning  and  deodorizing  before  entering  the 
storage  tank. 

When  the  water  in  the  can  is  frozen  it  is  taken  from  the  brine 
tank  by  a  crane  operated  by  compressed  air  to  a  can  dumper 
in  which  the  ice  is  freed  from  the  can  and  sent  to  the  ante- 
room, from  which  it  is  passed  into  the  ice-storage  room.  This 
room  is  cooled  by  a  coil  of  pipe  in  which  liquid  ammonia  is 
allowed  to  evaporate. 

Attention  is  called  to  the  insulation  of  the  freezing  tank 
and  the  ice-storage  room. 

The  table  below  gives  the  various  dimensions  of  York  plants 
of  different  sizes  with  necessary  data: 


. 

Lin.ft.  cf 

Tons. 

Boiler 
Room. 

Compression 
Room. 

Tank 
Room. 

Storage 
Room. 

Ante 
Room. 

H"  Exp. 
Coil  in 

300-lb, 

Wdth.  Lgth. 

Wdth.  Lgth. 

Wdth.  Lgth. 

Wdth.  Lgth. 

Wdth.  Lgth. 

Brine 

Cans. 

Tank. 

10 

IS    X   40 

25    X  40 

20    X  35 

20    X   27 

20    X      8 

2.500 

1  60 

20 

15    X  44 

25    X  44 

22     X    50 

22    X   40 

22     X     10 

5  ooo 

320 

30 

18    X    5'> 

25     X    5') 

28    X   53 

28     X    43 

28    X   10 

7,500 

480 

40 

1  8     X    5<"> 

25     X    Sfi 

•28    X  *2 

28    X   60 

28      X     12 

10,000 

640 

50 

18    X   56 

25    X   56 

28    X   97 

28    X    97 

12,500 

800 

18    X   56 

25    x  56 

28    Xi28 

28    Xi28 

18,750 

I2OO 

18    X   56 

25    X  56 

28    Xis8 

28    Xi58 

25,000 

1600 

Fig.  143  gives  the  outline  of  a  50- ton  Frick  can  ice  plant 
from  which  dimension  may  be  taken. 

In  Figs.  144  and  145  the  arrangement  of  a  plate  system 
for  50  tons  capacity  as  designed  by  the  Frick  Co.  is  shown. 
In  this  plant  a  producer  gas  engine  is  used  to  drive  the  com- 
pressor, as  raw  water  may  be  used  and  there  is  no  need  of  dis- 
tilled water. 

The  ammonia  is  compressed  in  a  vertical  compressor  and 
delivered  to  a  double-pipe  condenser  placed  on  the  second 
floor  of  the  engine  house,  Fig.  144.  From  the  condenser  it 
is  taken  into  a  receiver  A  in  the  freezing  room  near  the  wall 
and  then  delivered  to  a  header  B  running  along  the  freezing 
tanks.  In  the  figure  shown  there  are  seven  tanks  about  20  ft. 
long,  10  ft.  wide  and  10  ft.  deep,  each  well  insulated  against 


ICE  MAKING 


277 


278 


ELEMENTS  OF  REFRIGERATION 


ICE  MAKING  279 

heat  loss.  In  each  of  these  tanks  are  four  direct-expansion 
coils  supplied  from  a  header  connected  to  the  main  liquid  line. 
By  throttling  the  ammonia  is  allowed  to  enter  the  coil  and  the 
vapor  is  taken  off  from  the  mixture  leaving  through  the  main 
suction  pipe  C  at  the  top.  The  arrangement  of  feed  is  such 
that  there  is  much  liquid  left  in  the  coil  at  the  top  and  the 
mixture  is  taken  from  the  top  of  the  coil  to  an  accumulator  D 
where  the  vapor  is  separated,  the  liquid  passing  back  into  the 
lower  part  of  the  coils.  On  each  side  of  an  expansion  coil  is 
placed  a  heavy  sheet  of  steel  on  which  the  ice  forms.  This 
ice  forms  gradually,  taking  six  or  seven  days  to  make  12  ins. 
of  ice,  the  plate  weighing  about  6  or  7  tons.  As  the  ice  forms 
the  impurities  are  forced  ahead  of  the  ice,  leaving  clear  ice  from 
raw  water.  To  release  the  ice  when  ready  to  harvest,  the  liquid 
is  cut  off  from  the  coil  and  warm  vapor  is  allowed  to  enter 
from  the  header  Ey  this  melts  the  ice  from  the  plate  and  steam 
or  warm  brine  is  passed  through  pipes  placed  beneath  the 
tank  and  on  the  sides  to  melt  the  ice  from  the  sides  and  bottom 
of  the  tank.  This  is  the  only  function  of  the  thaw  pipes  shown 
in  Fig.  144. 

The  plate  of  ice  is  now  lifted  by  a  crane,  using  iron  rods 
frozen  in  the  ice  to  carry  the  load  and  after  placing  the  plate 
on  a  tilting  table  and  bringing  it  to  a  horizontal  position,  a  saw 
is  used  to  cut  the  ice  into  small  blocks.  The  saw  is  mounted 
on  a  motor  and  moves  on  a  sliding  table.  The  blocks  are 
stored  in  the  anteroom  or  in  the  main  storage  room. 

The  tanks  are  carefully  insulated  and  the  piping  beyond 
the  expansion  valve  is  covered  to  prevent  loss  of  refrigerating 
power.  The  tanks  are  well  braced.  The  arrangement  of 
piping  is  such  that  when  warm  ammonia  is  introduced  from  a 
special  line  the  condensed  ammonia  may  be  drawn  from  the 
coil  by  a  liquid  transfer  header.  The  liquid  ammonia  could 
go  to  one  of  the  coils  using  ammonia  liquid.  The  size  of  each 
tank  is  sufficient  to  give  the  complete  tonnage  of  the  plant 
for  one  day  so  that  this  tank  can  be  emptied  of  ice  and  filled 
with  fresh  water  the  same  day.  The  water  remaining  with 
the  impurities  is  taken  off.  This  would  require  that  the  num- 


280  ELEMENTS  OF  REFRIGERATION 

ber  of  tanks  equal  the  number  of  days  required  to  freeze  the 
ice  to  its  desired  thickness.  The  plant  shown  will  make  about 
50  tons. 

With  plate  ice  raw  water  may  be  used  and  there  is  no  need 
of  distilled  water.  Hence  high-grade  steam  engines,  gas  engines 
or  electric  motors  may  be  used  for  the  prime  movers.  The  use 
of  the  electric  motor  when  power  is  taken  from  a  central  station 
during  the  off-peak  hours  of  a  public  service  company,  furnishes 
a  cheap  method  of  driving,  as  the  off-peak  rate  may  be  very 
low.  The  Chicago  Edison  will  sell  off  peak  power  at  i  cent 
per  kilowatt  hour.  In  the  figures  shown  the  plant  is  driven  by 
gas  engines  throughout.  The  water-circulating  pump,  the 
agitator  blower,  the  air  pump  for  the  deep  well,  the  electric 
generator  and  the  filter  pump  are  driven  by  a  small  gas  engine. 
Air-storage  tanks  for  starting  the  gas  engines  are  placed  on  the 
side  of  the  room.  The  gas  producer  and  coal-storage  room 
may  be  seen. 

The  cold-water  storage  tank  is  used  to  cool  the  raw  water 
after  it  has  been  filtered.  This  filtering  is  resorted  to  to  take 
out  suspended  matter  and  bacteria. 

Having  the  general  arrangement  of  the  two  systems,  it  will 
be  advisable  to  examine  the  peculiar  apparatus  used  with 
each. 

The  distilled  water  apparatus  is  of  various  forms.  When 
there  is  sufficient  steam  from  the  engines  an  arrangement  is 
used  as  shown  in  Fig.  146.  This  is  that  used  by  the  York 
Mfg.  Co.  The  exhaust  steam  from  the  engine  passes  through 
an  oil  separator  and  feed-water  heater  and  then  to  a  condenser, 
where  it  is  condensed  by  water  used  in  the  ammonia  condenser. 
The  line  is  equipped  with  a  free  exhaust  valve  set  to  relieve 
the  pipe  after  a  certain  pressure  is  reached.  The  condensed 
steam  is  then  collected  in  a  return  tank,  from  which  it  is  pumped 
into  the  reboiler.  This  reboiler  is  operated  with  steam  from 
the  exhaust  main  or  from  live  steam  with  the  condensate  pass- 
ing to  the  exhaust  line.  After  reboiling  the  water  is  passed  to 
a  double-pipe  water  cooler  and  is  delivered  to  a  storage  tank 
after  passing  two  filters  and  a  regulator.  The  cooling  may  be 


ICE  MAKING 


281 


282 


ELEMENTS  OF  REFRIGERATION 


done  by  warm  condensing  water  from  the  condenser  or  by  a 
cool  supply.  .  The  amount  of  skimming  in  the  reboiler  regulates 


the  flow  of  water   through  the  system  by  taking  the  scum 
to  the  regulator. 


ICE  MAKING  283 

When  the  exhaust  steam  is  not  sufficient  to  supply  the  dis- 
tilled water  required,  some  form  of  evaporator  is  installed  by 
which  the  exhaust  steam  is  used  to  evaporate  water  and  thus 
increase  the  yield  of  distilled  water.  At  times  the  Lillie  evap- 
orator is  used,  although  any  type  may  be  employed.  A  single 
effect  evaporator  (one  evaporator  only)  is  in  general  sufficient 
for  an  ice  plant. 

The  arrangement  of  such  a  distilled  water  system  as  pro- 
posed by  the  De  La  Vergne  Co.  is  given  in  Fig.  147.  In  this 
the  exhaust  from  the  engine  passes  through  a  pipe  containing 
a  free  exhaust  valve  and  passing  through  a  grease  separator 
enters  the  space  around  a  set  of  tubes  in  a  vertical  evaporator. 
These  tubes  are  held  between  tube  plates  and  are  filled  with 
raw  water  which  rises  to  a  point  above  the  upper  tube  plate. 
The  condenser  B  has  a  vacuum  maintained  by  the  air-pump 
at  such  a  pressure  that  the  water  in  the  tubes  of  the  evaporator 
boils  and  passes  over  to  the  condenser.  The  boiling  of  the  raw 
water  removes  the  heat  of  the  exhaust  steam  and  this  con- 
denses around  the  tube  and  collects  on  top  of  the  lower  tube  plate. 
The  condensate  is  drawn  over  through  pipe  A  to  the  steam 
space  of  the  condenser  by  the  vacuum  in  B  and  is  allowed  to 
flow  by  gravity  into  the  vacuum  reboiler  which  is  connected 
at  the  top  to  the  steam  space  of  the  condenser.  The  air  pump 
G  is  connected  to  the  condenser  above  the  water  level  and 
removes  only  air  and  vapor.  The  reboiler  is  freed  from  water 
by  the  pump  H,  which  has  an  automatic  float  control  in  the 
reboiler.  The  reboiler  takes  live  steam  from  the  pump  supply 
and  the  condensate  from  the  coil  is  caught  in  a  reservoir  from 
which  it  is  drawn  by  the  vacuum  in  the  reboiler  whenever  the 
valve  K  is  opened  by  the  float. 

The  exhaust  steam  discharged  from  the  engine  may  be 
by-passed  around  the  evaporator  by  closing  D,  I  and  E  and 
opening  F  and  by  partially  opening  D;  when  F  is  partially 
opened  and  7  and  E  are  open,  some  of  the  engine  steam  is  allowed 
to  flow  to  the  condenser  without  evaporating  any  water.  In 
this  way  the  amount  of  distilled  water  is  regulated. 

The  reboiled  water  is  pumped  into  the  skimmer  and  then 


284 


ELEMENTS   OF  REFRIGERATION 


enters  the  hot-water  storage  tank  and  passes  successively 
through  the  cooler,  deodorizer  and  fore-cooler.  The  storage 
tank  for  hot  water  is  provided  with  a  float  so  that  when  this  water 


FIG.  148. — De  la  Vergne  Grease  Separator. 

is  low  the  butterfly  valve  on  the  final  discharge  pipe  is  closed 
and  prevents  water  from  being  drawn  away.  The  atmospheric 
water  cooler  is  cooled  with  water  which  may  be  used  later  for 
water  supply.  The  deodorizer  is  a  charcoal  filter  to  remove 


FIG.  149. — York  Reboiler. 

odor  and  certain  suspended  matter.  In  the  fore-cooler  the 
water  passes  from  it  through  a  set  of  pipes  which  are  cooled 
by  ice  water  flowing  over  the  set.  This  ice  water  is  pumped 
from  a  tray  beneath  the  coil  and  passed  first  over  pipes  which 


ICE  MAKING 


285 


contain  low- temperature  amm&nia  gas  or  ammonia  liquid. 
In  this  way  the  cooling  water  is  cooled  and  there  is  no  danger 
of  freezing  the  water  within  the  lower  pipes,  as  the  flowing 
water  cannot  reach  a  point  below  32  unless  it  freezes  on  the 
outside  of  the  ammonia  coils. 


FIG.  150. — De  la  Vergne  Reboiler  and  Skimmer, 

The  arrangements  in  these  figures  give  the  general  outline 
of  all  apparatus  for  distilled  water. 

The  arrangement  of  the  grease  separator  of  the  De  La 
Vergne  Co.  is  shown  in  Figo  148,  The  action. of  the  baffle 
plates  on  the  steam  and  oil  is  to  remove  the  oil  and  waten 

The  reboiler  of  the  York  Co.  is  shown  in  Fig.  149  while 
Fig.  150  gives  that  of  the  De  La  Vergne  Co.  In  each  of  these 
a  steam  coil  causes  the  water  to  boil  and  thus  drives  off  air  or 


286 


ELEMENTS  OF  REFRIGERATION 


other  gases,  while  the  oil  which'  forms  a  scum  is  taken  off  by  the 
skimming  edge  of  the  holes  at  the  right-hand  end  of  the  outlet 
chamber. 

The  filters  are  vessels  containing  a  layer  of  quartz  sand 


FIG.  151. — Sand  Filter. 

on  top  of  which  is  placed  charcoal.  This  removes  the  last 
suspended  matter  as  well  as  the  odor  and  taste,  and  in  order 
to  clean  this  an  occasional  supply  of  steam  can  be  admitted 
to  melt  off  the  oil  which  may  collect.  The  same  can  be  done 
to  the  pipes  of  the  condensed  water  cooler.  See  Fig.  147. 
When  raw  water  plants  are  used  the  filters  may  be  of  the 


ICE  MAKING 


287 


sand  type  as  shown  in  Fig.  151.  In  this  there  is  a  large  shell 
of  steel  containing  a  number  of  collecting  heads  in  a  lower 
diaphragm,  through  which  the  water  passes  after  traversing  a 
4-ft.  thickness  of  graduated  sand,  fine  at  the  top  where  the  water 
enters  and  coarser  as  the  bottom  is  reached.  By  introducing  a 
small  amount  of  alum  solution  from  the  coagulent  box  into  the 
water  in  inlet  pipe  the  suspended  matter  coagulates  and  collects 
on  top  of  the  bed.  This  collection,  known  as  the  "  schmutz- 
decke,"  gradually  becomes  so  thick  that  filtration  is  slow.  The 
current  is  then  reversed  by  valves  A  and  B,  the  water  entering 


FIG.  152. — Frick  Distilled  Water  Storage  Tank. 

from  the  bottom  by  E,  while  valve  D  is  closed  and  a  valve  to 
one  side  of  A  connects  the  top  to  the  sewer.  In  this  way  the 
washing  removes  the  deposit  from  the  filter.  A  glass  cup  shows 
the  condition  of  the  water  passing.  After  the  main  washing 
is  completed,  the  current  is  reversed  to  its  proper  direction 
and  the  discharge  allowed  to  waste  to  the  sewer  through  a  valve 
on  the  left  of  E  until  the  water  is  clear,  after  which  it  is  cut 
off  from  the  sewer  and  passed  back  to  the  line.  The  maximum 
amount  of  water  cared  for  by  such  filters  with  safety  is  2.5 
gallons  per  minute  per  square  foot  of  filter  bed. 

If  a  storage  tank  is  used  in  place  of  the  fore-cooler  the 
water  is  cooled  by  the  circulation  of  ammonia.     The  ammonia 


288 


ELEMENTS   OF  REFRIGERATION 


is  either  allowed  to  evaporate  in  a  coil  in  the  tank  or  the  cool 
ammonia  vapor  from  the  expansion  coils  is  taken  through  the 
coil  and  is  warmed  by  the  extraction  of  heat  from  the  water.  In 
this  way  ammonia  may  be  superheated  on  entering  the  com- 
pressor. Fig.  152  is  a  view  of  the  Frick  storage  tank  with  the 
coil  shown  as  if  the  tank  were  transparent. 

The  construction  of  the  freezing  tank  for  the  can  system 
of  the  De  La  Vergne  Co.  is  shown  in  Fig.  141.  The  inner 
partition  makes  a  circulation  from  an  agitator  positive,  as 
shown  by  the  arrows.  The  coils  are  arranged  so  that  two 


FIG.  153. — Frick  Flooded  System. 

are  controlled  from  one  branch.  In  the  figure  liquid  ammonia 
is  carried  to  the  bottom  of  the  coil  and  the  vapor  is  taken  from 
the  top.  This  is  the  arrangement  used  with  the  new  flooded 
system  which  has  been  introduced  within  the  last  few  years. 
As  shown  in  Fig.  153  this  system  consists  in  supplying  liquid 
to  the  lower  part  of  the  expansion  coil  in  large  quantities  so  that 
the  liquid  will  rise  through  a  vertical  branch  into  the  accumu- 
lator to  a  point  above  the  level  of  the  top  of  the  expansion 
coil.  Then  as  the  suction  pressure  is  decreased  by  the  action 
of  the  compressor  there  will  be  not  only  a  further  rise  in  the 
liquid  through  the  liquid  line  but  also  a  flow  of  vapor  and  liquid 


ICE  MAKING 


289 


through  the  upper  pipe  leading  from  tank  to  accumulator. 
The  accumulator  acts  as  a  separator,  allowing  the  liquid 
separated  to  flow  out  at  the  bottom,  while  the  dry  vapor  flows 
to  the  compressor  or  to  the  coils  of  the  filtered  water-storage  tank. 
The  level  of  liquid  in  the  accumulator  is  carried  near  the 
bottom  and  the  check  valve  leading  to  the  liquid  line  allows 
liquid  to  flow  from  the  accumulator. 

The  reason  for  the  employment  of  this  system  is  the  fact 
that  when  all  the  pipes  of  the  coils  have 
liquid  ammonia  in  them  they  are  all 
effective  and  moreover  there  is  a  slightly 
better  transfer  of  heat  due  to  a  high 
coefficient  for  liquid  to  liquid.  In  the 
ordinary  system  certain  of  the  upper  or 
lower  pipes  are  rilled  with  vapor  because 
of  the  danger  of  getting  liquid  into  the 
suction  line  and  as  a  result  these  pipes 
are  of  little  value  since,  after  the  liquid  is 
vaporized,  there  can  be  little  if  any  ab- 
straction of  heat,  because  the  brine  is  prac- 
tically at  the  same  temperature  as  the 
vapor.  Little  heat  can  be  abstracted  to 
superheat  the  vapor.  There  is  a  small 
amount  of  heat  transfer  in  these  pipes,  but 
small  because  the  ammonia  could  not  take 
up  the  heat  rather  than  that  the  coefficient 
is  small.  In  the  flooded  system  (invented 
by  J.  Krebs  in  1890)  liquid  ammonia  finds 
its  wav  to  the  highest  coils  and  although 
mixed  with  much  vapor  it  may  remove 
heat  from  the  last  foot  of  pipe.  As  a  result 
of  this  the  pipe  surface  necessary  for  a 
given  tonnage  may  be  decreased  from  300 


FIG.  154. — Ice  Can. 


lin.ft.  of  i|-in.  pipe  per  ton  to  180  feet  per  ton,  although  with 
longer  pipe,  not  absolutely  necessary,  the  efficiency  of  the  plant 
is  higher. 

The  structure  of  ice  cans  is  shown  in  Fig.  154.     The  various 


290 


ELEMENTS  OF  REFRIGERATION 


manufacturers  make  these  cans  in  about  the  same  shape  and 
size.     The  following  sizes  are  used  by  the  largest  manufacturers: 

ICE  CAN  DIMENSIONS 


Weight  of  Ice. 

Width  and 
Breadth  at 
Top. 

Width  and 
Breadth  at 
Bottom. 

Length  Inside 
Over  All. 

Galvanized  Iron, 
Thickness. 

SO 

8X8 

7iX   7* 

31           32 

No.  16  U.S.S. 

IOO 

8  Xi6 

7iXi5i 

31          32 

16 

20O 

111X22^ 

LO|X2I| 

31           32 

16 

300 

11^X22^ 

IO^X2l£ 

44          45 

16 

4OO 

II^X22i 

loixaii 

57          58                    14 

The  band  around  the  top  is  made  of  J  by  2 -in.  iron  for  the 
three  largest  sizes  and  J  by  i\  for  the  other  sizes.  The  iron 
is  turned  over  at  the  top  and  bottom  and  is  well  riveted  and 
soldered.  All  metal  is  galvanized. 

The  cans  are  handled  by  electric  hoists  or  air  hoists  as  shown 
in  Fig.  155.  These  are  mounted  on  light  traveling  cranes 
which  carry  the  tanks  to  the  ice  dump.  The  air  hose  or  electric 
cables  are  hung  from  roller  hangers  so  placed  that  the  loops 
will  not  reach  the  floor. 

The  ice  dump,  Fig.  156,  is  arranged  so  that  when  a  can  with 
ice  is  placed  within  it,  the  center  of  gravity  is  above  the  point  of 
support  and  it  may  be  easily  placed  in  an  inclined  position. 
This  motion  turns  on  the  water  sprinkler.  When  the  water 
has  melted  enough  ice  to  free  the  cake,  it  slides  out  and  leaves 
the  can  and  frame  in  such  a  condition  that  the  center  of  gravity 
is  below  the  support  and  the  frame  returns  to  the  vertical 
position,  automatically  shutting  off  the  water.  The  water 
which  issued  from  small  holes  in  the  pipe  is  caught  in  the  tray 
and  sent  to  the  sewer  and  the  ice  slides  free  of  all  contamina- 
tion. This  is  necessary,  as  the  brine  washed  from  the  outside 
of  the  can  should  not  come  in  contact  with  the  ice. 

.The  latest  improvement  in  the  can  system  of  ice  making 
has  been  the  use  of  raw  water  for  can  ice.  There  have  been 
numerous  methods  suggested  for  the  production  of  clear  ice 
from  raw  water.  The  raw  water  can  ice  of  the  earlier  day  was 
quite  opaque  and  although  as  valuable  for  cooling  as  clear 


ICE  MAKING 


231 


IJG.  155. — Can  Hoists. 


FIG.  156.— Frick  Can  Thawing  Dump. 


292 


ELEMENTS   OF  KEFRIGERATION 


ice  this  opaque  ice  would  have  little  if  any  value  for  domestic 
service.  When  the  water  was  filtered  the  cake  would  be  fairly 
clear  if  little  air  was  present  except  for  the  central  core,  and 
hence  proposals  were  made  to  form  a  large  cake  and  then  cut 
this  into  four  pieces  on  lines  passing  through  the  core,  placing 
the  opaque  part  on  one  edge.  It  was  also  proposed  to  freeze 
all  but  the  core  and  then  to  remove  this  water  containing  the 


FIG.  157. — Double  Drop  Tube.     De  la  Vergne  Co. 

impurities  and  introduce   enough  distilled  water   to  nil   this 
space. 

To  prevent  the  formation  of  opaque  ice  it  was  found  neces- 
sary to  agitate  the  water  while  freezing  to  prevent  the  reten- 
tion of  the  small  air  bubbles  which  cause  the  whiteness.  One 
method  of  agitating  this  water  (patented  in  Italy  in  1877  by 
Turretini)  is  to  introduce  air  at  the  bottom  of  the  can  at  a  pres- 
sure slightly  above  that  due  to  the  water  depth  and  this  air 
jet  produces  necessary  agitation.  The  air  is  introduced  at  the 
center  of  the  bottom  as  shown  in  Fig.  160  entering  in  one  of 
several  patented  ways.  In  Fig.  157  the  air  is  introduced  by 


ICE  MAKING 


293 


a  drop  tube.  The  tubes  are  connected  to  a  tee  which  is  placed 
on  an  air  outlet  of  the  air  pipe  running  between  every  other 
pair  of  cans  on  the  framework  which  carries  the  top  of  the 
tank.  The  connection  to  the  air  main  is  made  so  that  the  drop 
tubes  may  be  withdrawn  from  an  automatic  self-closing  valve, 


Rotary  Blower       Core  Pump 


FIG.  158. — Plan  of  De  la  Veigne  Raw  Water  Ice  Plant. 

which  prevents  air  discharge  when  the  connection  is  removed. 
As  the  impurities  gradually  collect  at  the  center  in  the  core 
space  they  are  finally  drawn  out  by  the  core  pumps  and  the 
space  filled  with  distilled  water  or  good  clear  raw  water  which 
has  been  filtered  as  carefully  as  the  original  water  used. 

The    general    arrangement    of    the    core-pump    hose    and 
refilling  hose  is  shown  in  Fig.  158.     In  this  figure  will  be  seen 


294 


ELEMENTS  OF  REFRIGERATION 


ICE  MAKING  295 

the  general  arrangement  of  one  air-supply  header  running  from 
the  main'  header  which  receives  air  from  the  rotary  blower. 
The  core  pump  is  connected  to  two  lines  of  hose  which  may 
be  put  in  any  can  for  the  removal  of  the  core  water.  This 
amounts  to  about  10  Ibs.  in  3oo-lb.  cans.  The  water  from 
the  fore  cooler  is  attached  to  four  large  hose  lines  for  filling 
tanks  and  to  two  small  ones  for  filling  the  cores,  the  same 
water  being  used  for  each  purpose.  The  motors  driving  four 
agitators  are  shown  in  the  figure. 

The  air  taken  into  the  blower  is  first  cooled  to  remove  the 
moisture  from  it  so  that  this  moisture  will  not  freeze  in  the  air 
headers  or  drop  tubes.  The  air  is  taken  from  the  atmosphere 
at  a  high  point  in  the  plant  and  passed  to  a  header  from  which 
it  enters  a  series  of  pipes,  Fig.  159,  over  which  water  near 
32°  F.  is  passed.  In  this  way  the  air  is  cooled  and  the  moist- 
ure in  the  air  is  condensed  and  dripped  from  the  collecting 
header  before  the  air  enters  the  air  main.  The  air  may  be 
taken  through  a  screen  to  remove  dust  or  any  form  of  air 
cleaner  may  be  used.  The  water  is  taken  by  a  small  centrif- 
ugal or  rotary  pump  from  the  cold-water  storage  tank  and  dis- 
tributed over  the  air  coil,  after  which  it  falls  over  an  ammonia- 
expansion  coil,  which  cools  it  to  about  32°  F.  This  water  is 
then  collected  in  the  tank  from  which  it  is  pumped  to  the  cans 
as  needed  or  back  over  the  air  coil.  The  air  thus  dried  will 
not  clog  the  drop  tubes  as  it  enters  and  meets  the  cold  walls 
of  the  tube.  The  pressure  necessary  for  3oo-lb.  cans  is  about 
2  Ibs.  per  square  inch,  due  primarily  to  the  amount  of  sub- 
mergence of  the  end  of  the  drop  tube.  This  air  keeps  the 
water  agitated  and  thus  wipes  off  any  bubbles  of  air  which 
might  cling  to  the  surface  of  the  ice. 

In  Fig.  1 60  the  tube  A  is  fastened  to  the  side  of  the  can 
and  in  this  the  air  is  forced  from  the  end  B  through  the  ice 
as  it  forms,  leaving  a  small  seam  through  which  air  flows,  driving 
the  water  out  of  it  and  keeping  the  water  above  agitated  and 
driving  the  impurities  gradually  to  the  top  D  of  the  can.  This 
leaves  the  hollowed  top  of  ice  with  all  impurities  above  the  grid 
F  in  the  unfrozen  water.  This  water  is  thrown  away  when 


296 


ELEMENTS   OF  REFRIGERATION 


the  can  is  taken  out  and  the  grid  with  the  ice  on  it  is  removed, 
leaving  clear  ice  of  uniform  length  for  storage.  The  grid  also 
serves  to  freeze  the  center  cup  at  the  end  due  to  the  conduction 
of  the  iron.  In  this  system  the  pressure  has  to  be  increased  as 
the  ice  forms.  This  of  course  is  automatic  through  the  use  of  a 
valve  which  throttles  the  air  discharge  until  resistance  is  brought 


FIG.  160.— York  Raw  Water  Can. 

on  by  the  formation  of  ice.  The  pressure  at  the  pump  remains 
constant,  being  used  up  in  pipe  and  valve  friction  when  first 
applied,  and  finally  the  ice  friction  requires  the  full  pressure 
as  the  ice  closes  in.  The  gauge  pressure  is  about  18  Ib.  per 
square  inch.  The  power  used  in  the  compressor  is  about  0.4 
H.P.  per  ton  of  capacity.  The  air  used  amounts  to  1.8  cu.ft.  per 
can  per  minute  at  start  to  0.3  cu.ft.  per  minute  after  freezing. 


ICE  MAKING  297 

The  two  methods  described  are  those  used  by  two  large 
manufacturers.  There  are  many  other  methods  employed  which 
have  given  satisfaction.  For  instance,  the  agitation  has  been 
accomplished  by  drawing  water  from  the  core  and  then  allow- 
ing it  to  discharge  back  again,  th'.s  back  and  forth  motion  pre- 
venting the  formation  of  opaque  ice.  One  of  the  first  methods 
was  to  rock  the  cans  and  after  this,  agitation  was  by  rods  and 
then  by  air  discharge.  Another  method  patented  by  Ott  Jewell 
is  an  ice  can  in  which  the  brine  is  passed  through  a  double 
wall  of  the  can  and  air  is  introduced  at  bottom  to  agitate.  The 
Beal  patent  of  1913  is  similar  to  the  York  method  described 
above.  The  Ulrich  patent  brings  the  air  pipe  in  on  the  out- 
side of  the  can. 

The  plate  system  accomplishes  the  result  of  the  raw-water 
can  system  without  the  complication  of  air-pump  or  rocking 
apparatus.  On  account  of  the  increased  space  and  an  increase 
of  about  30  to  70%  in  the  initial  cost,  due  to  the  larger  building, 
the  plate  system  is  not  installed  as  frequently  as  the  can  system. 
In  1915  the  De  La  Vergne  Company  stated  that  there  were 
150  plate  plants  in  operation  in  the  United  States.  Of  course 
with  the  plate  system  almost  any  kind  of  water  may  be 
used. 

The  generation  of  the  liquid  ammonia  may  be  accomplished 
by  an  absorption  system  as  well  as  the  compression  methods 
described.  The  arrangement  of  the  ice  apparatus  is  practically 
the  same  when  the  absorption  system  is  used  to  compress  the 
ammonia.  If  an  absorption  system  is  placed  where  compres- 
sors are  shown  in  the  previous  figures  the  apparatus  would 
be  that  used  by  the  makers  of  that  type  of  apparatus  for  ice 
making. 

There  are  more  than  one  thousand  plants  in  the  United 
States,  of  which  about  81%  are  operated  by  compression  and 
1 8%  by  absorption.  The  output  of  these  is  over  twenty- 
three  million  tons  of  ice.  The  natural  ice  crop  is  probably 
equal  to  or  greater  than  this.  The  curve  of  delivery  of  ice 
will  follow  the  curve  cf  temperature  difference  above  32°  F., 
although  there  may  be  some  changes  due  to  manufacturing 


298 


ELEMENTS   OF  REFRIGERATION 


or  other  application  of  ice.  In  any  case  it  is  well  to  draw  a 
consumption  curve  to  be  expected  or  known  from  previous 
records.  From  this  curve  the  capacity  of  the  plant  and  the 

size  of  the   storage   room  may  be 
found. 

These  various  methods  are  ap- 
plicable in  special  cases.  The  plate 
system  is  advisable  with  expensive 
fuel  and  very  poor  water,  while  with 
better  water  the  raw- water  can  sys- 
tem may  be  used.  When  fuel  is 
cheap  the  distilled  can  system  may 
be  used  and  when  there  is  exhaust 
steam  from  other  machines  the  ab- 
sorption system  should  be  employed. 
The  absorption  system  may  be 
operated  in  an  isolated  plant  with 
economies  as  good  as  the  compres- 
sion system. 

The  water  for  ice  plants  is 
usually  taken  from  deep  wells.  The 
wells  are  rarely  artesian  and  the 
water  has  to  be  pumped.  The  pumps 
are  of  various  forms.  Deep-well 
pumps  have  a  pump  bucket  operated 
at  the  end  of  a  long  rod  by  a  steam 
piston  in  engine  room,  Fig.  161.  An 
air-lift  pump  is  one,  Fig.  162,  in 
which  compressed  air  is  allowed  to 
enter  the- water  pipe  and  by  aerat- 
ing the  column  of  air  and  making 
it  lighter  than  the  water  outside  of 
FIG.  161.— Deep-well  Pump.  the  casing  it  drives  the  water  out  of 

the  discharge  main.     Other  pumps 

are  used.  The  air-lift  pump  has  the  advantage  of  being  simple 
to  install,  and  of  having  all  of  the  working  parts  accessible  as 
well  as  being  able  to  deliver  a  large  quantity  from  a  given  well. 


ICE  MAKING 


299 


FIG.  162. — Air-lift  Pump. 


Exhaust  Steam 


Drain 


Drain 


FIG.  163. — Oil  Separators. 


300  ELEMENTS  OF  REFRIGERATION 

It  is  very  inefficient  in  the  use  of  power  and  hence  is  more  expen- 
sive to  operate.  Its  advantages  are  such,  however,  that  the 
pump  is  extensively  used. 

The  power  to  drive  a  deep-well  pump  may  be  figured  from 
the  quantity  Mw  and  the  lift  H  as 

H.P.  for  deep-well  pump  = ^—^r- 

55oXerL 

Mw  =  weight  of  water  per  second  in  pounds  per  second; 
H  =  height  in  feet  from  water  level  in  well  to  discharge 

nozzle ; 

Eff.  =  70%  for  deep-well  pump  from  steam  to  water; 
=  30%  for  air-lift  pump  from  compressor  motor  to 
water. 

u-    t         tt  WxH 

Air  per  minute  in  cubic  feet  of  free  air  =  —  — — . 

10. 0 

W  =  cubic  feet  of  water  per  minute. 

To  treat  water  from  which  the  oil  cannot  be  removed  in 
the  ordinary  way  A.  A.  Gary  suggests  in  the  Transactions  of  the 
American  Society  of  Refrigerating  Engineers  to  pass  the  water 
through  a  long  coke  filter,  or  to  pass  the  steam  through  a 
steam  washer  in  which  the  steam  has  to  pass  through  water 
or  over  water  as  shown  in  Fig.  163.  An  enlarged  chamber  on 
the  steam  main  to  cut  down  the  velocity  of  the  steam  and  per- 
mit the  steam  to  come  in  contact  with  a  series  of  screens  was 
also  suggested. 

In  planning  for  the  amount  of  distilled  water  for  an  ice 
plant  an  allowance  of  a  waste  of  25%  of  that  turned  into  ice 
must  be  made. 

If  the  amount  of  steam  from  the  various  machines  is  not 
sufficient  to  supply  the  necessary  distilled  water  some  form  of 
evaporator  as  shown  in  Fig.  147  must  be  used.  Fig.  164 
shows  the  form  of  Lillie  evaporator.  In  this  exhaust  steam 
from  the  engine  and  other  auxiliaries  is  discharged  at  H  and 
enters  the  tubes  E,  which  have  a  reduced  oressure  within,  due  to 
the  suction  through  the  small  holes  drilled  in  the  caps  of  the 
left-hand  end  of  each  of  them  from  the  low  pressure  which 


ICE  MAKING 


301 


exists  in  B.     This  low  pressure  is  caused  by  a  vacuum  pump 
attached   to   a   condenser   which  is  joined  to  the  evaporator 


by  the  pipe  N.  Water  from  the  sump  K  is  pumped  by 
the  centrifugal  pump  L  through  M  to  the  G  box  whence  it 
discharges  through  eleven  pipes  F  and  falls  over  the  pipes  E. 


302  ELEMENTS  OF  REFRIGERATION 

This  water  is  heated  and  condenses  some  of  the  steam  inside 
of  the  tube  E,  and  the  pressure  is  so  reduced  that  the  water  will 
boil  at  a  lower  temperature  than  that  of  the  steam  inside.  The 
evaporation  of  this  water  will  cause  further  condensation 
of  the  steam  inside.  The  condensed  steam  drops  to  the  front 
of  C  and  is  removed.  As  the  water  in  the  shell  is  evaporated 
the  sump  box  K  does  not  contain  enough  water  to  lift  the  float 
and  hence  more  water  is  introduced.  When  the  water  in  A 
becomes  heavy  with  salts  after  evaporating  a  lot  of  water, 
the  heavy  liquid  is  removed  by  opening  R. 

To  compute  the  necessary  surface  and  size  of  evaporator 
the  following  equations  may  be  used: 

From  the  equation 

M,(i't-i'0)=M»(i''t-i"0)+Qe,     .     .     .     (i) 

the  amount  of  water  Mw  from  the  steam  Ms  is  found.  In 
this 

Ms  =  weight  of  steam  condensed  per  hour; 
Mw  =  weight  of  water  evaporated  per  hour; 
Qe  =  heat  radiated  from  covered  evaporator,  computed 

from  Chapter  V; 
i'i  and  i'o  =  heat   contents   of   dry   steam   entering   and    water 

leaving  at  pressure  of  exhaust  steam; 

i'fQ  and  i"  i  =  heat  contents  of  dry  steam  leaving  at  pressure 
assumed  in  B  (20°  less  than  entering  steam)  and 
of  the  entering  water. 

The  surface  is  figured  by 

„    Mw(i'i-i'o)  ,  , 

~  '     ' 


to  =  temperature  of  entering  steam; 
/'o  =  temperature  of  steam  leaving; 
K  =  400. 

An  important  consideration  in  planning  an  ice  plant  is  the 
sanitary  condition  around  the  plant.  Since  ice  is  to  be  used 
for  domestic  purposes  and  may  be  introduced  into  food  or 


ICE  MAKING  303 

drink,  it  is  necessary  that  cleanliness  be  insisted  upon.  The 
men  walk  over  the  covers  of  the  cans,  and  dirt  on  the  footwear 
may  fall  into  the  cans,  hence  there  should  be  no  chance  for 
the  workmen  employed  in  harvesting  from  going  through 
places  when  contamination  may  occur.  The  floor  of  water- 
closets  for  instance  should  be  kept  so  clean  that  nothing  can  cling 
to  the  footwear.  The  water-closets  should  not  be  placed  so 
that  workmen  would  have  to  pass  through  stable  yards  or 
over  roadways  to  reach  them.  In  many  ice  plants  conditions 
exist  such  that  men  must  pass  through  regions  where  the  boots 
take  up  this  contaminating  matter.  The  condition  of  the  water- 
closet  should  be  bright  and  clean.  Money  spent  here  on  tile 
work  and  terazzo  flooring  is  not  wasted. 

The  wells  or  springs  from  which  the  water  is  taken  must  be 
placed  so  that  they  may  not  be  contaminated  by  materials 
blown  by  the  winds  or  from  ground  or  subsurface  seepage. 
The  use  of  cesspools  for  water-closets  should  not  be  tolerated, 
especially  where  wells  or  springs  are  used  for  water  supply. 

To  keep  the  plants  clean  they  must  be  so  constructed  that 
dirt  will  show,  and  hence  the  covers,  walls  and  all  parts  of  the 
plant  should  be  painted  white.  It  is  also  advisable  to  have  no 
one  walk  over  the  tank  tops  who  does  not  put  on  rubber  over- 
shoes which  are  not  worn  anywhere  else. 

Freezing  Tanks.  Freezing  tanks  are  usually  made  of  steel 
plate  with  insulation  beneath  and  around  them.  This  is  shown 
in  Fig.  141.  The  insulation  is  sufficiently  heavy  to  cut  down 
the  heat  loss  to  a  low  value.  The  thickness  is  fixed  by  finding 
the  minimum  yearly  cost  due  to  heat  loss,  interest,  depreciation, 
taxes,  insurance  and  maintenance.  The  tanks  for  the  plate 
system  are  sometimes  made  of  timber.  These  must  be  care- 
fully braced  whether  of  wood  or  metal  because  of  the  depth. 
Reinforced  concrete  has  been  used  for  brine  tanks.  The  bottom 
and  sides  are  made  of  6  or  8  ins.  of  concrete  with  f  in.  reinforc- 
ing bars  placed  i  ft.  apart  and  2  ins.  within  the  concrete  from 
the  brine  side.  This  is  followed  by  2  ins.  of  cork  board  and 
then  five  layers  of  tar  felt  put  on  with  hot  coal  tar,  on  top  of 
which  is  placed  2  ins.  of  concrete  with  a  smooth  finish.  To  cut 


304 


ELEMENTS  OF  REFRIGERATION 


down  the  heat  transfer  a  thick  layer  of  cinder  may  be  used 
around  the  tank,  16  ins.  of  dry  cinder  being  equal  to  2  ins. 
of  cork.  There  is  a  difference  of  opinion  as  to  the  advisability 
of  using  concrete  for  the  brine  tank,  as  some  claim  calcium 
chloride  disintegrates  the  concrete,  but  others  say  that  concrete 
is  perfectly  satisfactory. 

In  planning  the  size  of  brine  tanks  the  time  of  freezing  must 
be  assumed  and  sufficient  cans  or  plate  tanks  must  be  installed 
to  give  the  required  capacity.  In  plate  work  one  freezing  tank 
should  be  large  enough  to  give  the  required  output.  If  the 
weight  of  ice  is  taken  57^  Ibs.  per  cubic  foot,  the  volume  of  the 
plates  for  the  given  tonnage,  assuming  a  thickness  of  12  or 
14  ins.,  may  be  found,  and  from  this  the  volume  of  the  tank,  the 


Reinforcement 
Concrete 


FIG.  165. — Reinforced  Concrete  Brine  Tank. 

depths  being  about  10  ft.  and  the  widths  16  ft.     The  time  of 
freezing  the  plate  ice  is  given  by  Macintire  as 

2 1  a2 


(3) 


h  =  hours  of  freezing; 

a  =  thickness  in  inches; 

//=  temperature  in  refrigerating  pipes  in  deg.  F. 

This  takes  about  six  days,  so  that  six  or  seven  tanks  are 
used.  The  number  of  cans  is  found  in  the  same  way.  If  the 
smaller  thickness  of  the  can  is  represented  by  a,  then  the  time 
is  given  by  Macintire  as 

h  =  ^.  (4) 


a  =  thickness  of  can  at  top  in  inches. 


ICE  MAKING 


305 


In  this  way  the  total  output  during  the  freezing  is 

/?Xtons 

24 

And  the  number  of  cans  is  given  as 
//  X  tons 


24XWt.  per  can 


=  number  of  cans. 


-     (5) 


Ordinarily  fourteen  3oo-lb.  cans  are  used  per  ton  of  capacity. 
This  means  fifty  hours  for  the  formation  of  the  ice.  If  the 
number  of  cans  is  increased  it  means  that  there  is  a  longer  time 
for  the  ice  formation  and  hence  a  smaller  difference  in  brine 
and  water  temperatures,  which  means  a  higher  back  pressure 
and  less  work,  while  a  decrease  in  the  number  means  a  lower 
brine  temperature  to  give  the  smaller  time  for  freezing.  This 
means  a  lower  back  pressure  on  the  compressor  and  hence  more 
work.  It  is  well  to  compute  the  yearly  cost  of  ground,  build- 
ing and  equipment  against  the  cost  of  power  in  figuring  the 
number  of  cans.  To  compute  the  temperature  of  the  brine  a 
value  of  2.6  for  K  is  used.  This  same  thing  is  true  in  regard 
to  the  number  of  tanks  in  the  plate  system.  To  show  this 
Thomas  Shipley  has  computed  the  following  table: 

EFFECT  VARIATIONS  IN  CAN  ALLOWANCE  HAVE  ON  HORSE-POWER  REQUIRED 
TO  PRODUCE  ONE  TON  OF  ICE.     (With  Single-acting  Compr.) 


I 

2 

3 

4 

5 

6 

No.  300-lb. 
Cans  Per 
Ton  Ice 
Making. 

Average  Brine 
Temperatures 
Needed  to 
Produce  Ice. 

Rate  of  Heat 
Transmission 
B.T.U.   per 
Sq.ft.  per  Hr. 
i°  MD. 

Temperature 
Required  in 
Pipe. 

Corresponding 
Evaporating 
G.  Pressure. 

Total  Brake 
H.P.  per  Ton 
Ice  Making 
185  Lbs.  C.  P. 

°F. 

for  Pipes. 

op 

Lbs. 

IO 
12 

14 

7 
ii 

14 

•15 
15 

-3-3 
.        +0.7 
3-7 

13-3 
16.2 

2-77 
2  -.45  .. 

18 

16 
18 

15 

5-7 
7-7 

20 

21.7 

2-352 

2.27 

Note. — Evaporating  surface  in  the  freezing  tank  assumed  in  this  table  is 
108  sq.ft.  or  250  ft.  of  ij-in.  pipe  per  ton  of  ice. 

Note. — Tables  are  based  upon  the  water  to  be  frozen  being  delivered  to  the 
cooling  and  freezing  system  at  70°  F. 

Work  done  by  cooling  system  =30  B.t.u.  per  pound  of  ice. 

Work  done  by  freezing  system  =  200  B.t.u.  per  pound  of  ice. 


306  ELEMENTS   OF  REFRIGERATION 

Expansion  Coils.  In  the  coils  of  brine  tanks  the  liquid 
ammonia  may  enter  the  upper  or  lower  pipe.  When  the  flooded 
system  is  used  the  liquid  is  introduced  at  the  bottom,  and  it 
seems  unreasonable  to  bring  it  in  at  any  other  point  if  the  coil 
is  to  receive  its  full  supply  of  liquid.  In  this  case  the  vapor 
header  may  be  drained  to  the  low  liquid  line  to  return  any 
liquid  unevaporated.  This  really  gives  a  flooded  system. 
Before  the  wide  introduction  of  the  flooded  system  there  was  a 
great  difference  of  opinion  over  this  point  among  the  refriger- 
ating engineers,  but  this  matter  seems  to  be  settled  by  the 
adoption  of  the  flooded  system. 

In  some  cases  the  brine  may  be  cooled  in  a  brine  cooler 
on  one  of  the  types  shown  in  Figs.  19,  8 1  and  82  and  the  brine 
pumped  to  the  freezing  tank.  Such  a  device  is  not  so  good 
as  the  use  of  expansion  coils  in  the  freezing  tank,  as  this 
method  keeps  the  brine  at  a  low  temperature  throughout  by 
abstracting  heat  from  it  as  it  abstracts  heat  from  the  freezing 
water. 

The  amount  of  this  surface  in  a  brine  tank  is  figured  by 
allowing  a  value  of  K  of  15  due  to  the  low  velocity  of  the  brine 
over  the  coils.  In  a  brine  cooler  especially  of  the  double  pipe 
type  or  the  shell  type  a  much  higher  value  of  K  is  used,  due  to 
the  higher  velocity  of  the  brine.  Since  this  method  is  rarely 
used  the  case  of  the  expansion  coil  in  the  tank  will  be  con- 
sidered. It  has  been  found  that  120  to  150  lin.ft.  of  i^-in. 
pipe  is  sufficient  to  care  for  a  ton  capacity  with  ordinary  coils 
and  about  80  ft.  have  been  found  necessary  in  the  flooded 
system.  In  any  case  it  is  a  matter  of  abstracting  the  heat  and 
if  the  surface  is  cut  down  the  back  pressure  must  be  decreased 
to  give  the  necessary  temperature  difference.  This  means 
greater  power  for  the  same  refrigeration.  One  must  compute 
the  yearly  cost  on  investment  on  pipe  against  the  cost  of  power. 
Assuming  sixteen  cans  per  ton,  Thomas  Shipley  has  computed 
a  table  showing  the  effect  of  change  of  pipe  length. 

The  powers  required  are  the  powers  applied  to  the  compres- 
sors to  drive  them,  whether  by  belt,  direct-connected  motor  or 
engine.  The  auxiliaries  require  about  0.3  to  0.4  H.P. 


ICE  MAKING 


307 


EFFECT  OF  VARIATIONS  IN  EVAPORATING  SURFACE  ON  HORSE-POWER  REQUIRED 
TO  PRODUCE  ONE  TON  OF  ICE  WITH  SINGLE-ACTING  COMPRESSOR. 


I 

2 

3 

4 

5 

6 

7 

Lineal  Ft. 
of  ij-in. 
Pipe  per 
Ton  of  Ice 
Making. 

Sq.ft.  Pipe 
Surface, 
External. 

Rate  of 
Heat  Trans- 
fer for 
Pipe  =  K. 

Average 
Tempera- 
ture of 
Brine. 

Tempera- 
ture in 
Pipe. 

Gauge  Press 
in  Coil. 

Total  Brake 
H.P.  per 
Ton  of  Ice 
Making  at 
185  Lbs. 
Comp.  Pres. 

°F. 

F» 

Lbs. 

150 

65 

IS 

16 

—  i.i 

14.85 

2.661 

2OO 

87 

15 

16 

3-2 

18.1 

2.468 

250 

108 

IS 

16 

5-7 

20.  o 

2.352 

300 

130 

IS 

16 

7-45 

21.5 

2.279 

350 

152 

IS 

16 

8.7 

22.5 

2.218 

The  pressure  of  compression  has  an  important  bearing  on  the 
efficiency  of  the  plant.  An  endeavor  should  be  made  to  use  as 
cool  water  as  possible  for  the  condenser  to  keep  this  pressure 
low.*  The  effect  of  this  is  seen  in  the  following  table  by  Thomas 
Shipley: 

POWER  REQUIRED  PER  TON  OF  ICE  AT  DIFFERENT  CONDENSING  PRESSURES 
WITH  A  SINGLE-ACTING  COMPRESSOR  WORKING  UNDER  A  SUCTION  PRESS- 
URE OF  20  LBS. 


Condensing  pressure 

85 

105 

125 

145 

165 

185 

205 

225 

245 

Corresponding  Tem. 

47.6 

58.6 

68.1 

76.6 

84.2 

91  .0 

97.3 

103.2 

108.9 

H.P.  per  ton  of  ice  .  . 

i  .  162 

1.408 

i  .646 

1.874 

2.114 

2.352 

2.587 

2.851 

3-098 

The  rule  for  the  number  of  tanks  and  size  of  the  expansion 
coil  has  been  worked  out  on  the  assumption  of  200  B.t.u. 
per  pound  of  ice  in  the  freezing  tank  and  30  B.t.u.  per  pound 
in  the  cooling  tank.  Of  course  there  are  average  results,  but 
in  some  cases  the  quantity  must  be  computed  owing  to  peculiar 
conditions.  The  heat  to  be  removed  in  the  cooling  system 
per  pound  of  ice  made,  if  15%  excess  is  allowed  and  water  is 
at  t°  F.  and  is  to  be  cooled  to  32  is 


.    ......     (6) 

*  If  water  has  to  be  pumped  and  is  bought,  a  calculation  must  be  made  for 
the  cost  of  water  and  of  power  for  the  compressor  and  for  the  pump  for  different 
quantities  of  water  and  the  one  giving  the  best  result  used. 


308 


ELEMENTS  OF  REFRIGERATION 


The  heat  of  fusion  is  143.4  B.t.u.  and  the  specific  heat  of 
ice  is  given  by 


c  —  specific  heat  ice; 

t  =  temperature  of  ice  in  degrees  C. 

This  has  been   tabulated  by  Dickinson    and   Osborne  as 
follows : 

HEAT  TO  FREEZE  ONE  LB.  OF  WATER  AT  32°  AND  TO  COOL  ICE  TO  TEMPERATURE. 


t 

Q 

t 

Q 

t 

Q 

—  20 

167.  2 

—  2 

159-5 

16 

151.2 

-18 

166.3 

0 

158.6 

18 

150-3 

-16 

I65-5 

2 

157-7 

20 

149-3 

—  14 

164.7 

4 

156.8 

22 

148.4 

—  12 

163.8 

6 

155-9 

24 

147-4 

—  10 

163.0 

8 

155-0 

26 

146.4 

-   8 

I62.I 

10 

I54-I 

28 

145-4 

-  6 

l6l.3 

12 

I53-I 

3° 

144.4 

-  4 

160.4 

14 

152.2 

32 

143-4 

The  heat  used  then  will  be 

i. t$Qf=Q  =  1. 15 x  160  =  184  B.t.u.  approx.     .    .     (8) 

Although  only  184  B.t.u.  are  needed,  the  radiation  will  be 
an  additional  amount,  making  200  B.t.u.,  used  by  Shipley. 
The  radiation  loss  may  be  computed. 

The  size  of  pipes  for  brine,  ammonia  and  water  are  com- 
puted by  method  of  Chapter  VI. 

From  the  curve  of  ice  consumption,  as  shown  in  Fig.  166, 
the  main  demand  for  ice  can  be  found  and  the  question  arises: 
Is  it  better  to  put  in  enough  ice-making  capacity  to  carry  the 
peak  load,  having  idle  machinery  during  a  large  part  of  the  year, 
than  to  install  apparatus  for  the  mean  capacity  and  operate 
at  this  capacity,  storing  at  time  of  low  demand  to  carry  the 
amount  demanded  at  times  above  the  mean  curve?  This 
problem  is  one  which  can  be  computed.  The  extra  apparatus 


ICE  MAKING 


309 


and  plant  needed  beyond  that  for  mean  load  is  found  and  the 
cost  of  interest,  depreciation,  taxes  and  insurance  is  compared 
with  the  cost  of  storing,  loading  and  removing  ice,  including 
the  cost  of  the  building. 

To  store  ice  and  hold  it  from  spring  to  midsummer  and  then 
take  it  from  storage  costs  25  to  30  cents  per  ton  according  to 
W.  E.  Parsons.  J.  N.  Briggs  increases  this  by  the  yearly  cost 
of  the  storehouse,  15  cents  brings  the  cost  to  40  or  45  cents 
per  ton.  This  includes  the  expense  of  holding,  and  in  this 


AUU 

300 
200 

23°F. 

23°F. 

33°  F. 

46  F. 

59°  F. 

68° 

73° 

71° 

63° 

51° 

• 

39° 

28° 

Mean 

Height 

100 

Jan, 


Mar.       Apr, 


June       July 
Months 


Aug.      Sept       Oct. 


FIG  166.  —  Curves  of  Tons  per  Day.    Arranged  for  months  for  Troy,  N.  Y. 
Monthly  average  temperature  for  forty  years. 


problem  the  cost  of  insulation  isj^ompared  with  Hjat  qf  absorb  - 

ing  the  .heat  transferred  to  determine  the  amount  of  insula- 
tion. After  this  is  fixed  the  amount  of  heat  loss  is  found  and 
cared  for  by  melting  ice  or  by  refrigerating  coils.  The  latter 
method  is  the  better,  as  it  is  cheaper  to  cool  the  room  than  to 
make  an  equivalent  amount  of  ice  to  do  this.  The  data  from 
a  storehouse  of  this  kind  will  be  mentioned. 

From  the  amount  of  heat  to  be  supplied  by  the  brine  coils 
in  the  freezing  the  surface  may  be  computed  by  assuming  the 
temperatures  of  the  water  in  cans,  brine,  and  ammonia.  Call 
these  tw,  /&,  and  ta, 


310  ELEMENTS  OF  REFRIGERATION 

Can  surface  in  sq.ft.  per  ton  of  ice 

_2oooX[i.i5Q/+Qr]  _  6410  . 

Coil  surface  in  sq.ft.  per  ton 

_2oooX[i.i5(?/+(?r]  _  mi  (    ^ 

n — ~~; — T vIOJ 


The  amount  of  refrigeration  for  plant  per  ton  of  ice 

=  [ft+i.i5Q/+(?r]2ooo 
199.2X24 


249 

An  ice-storage  plant  in  Philadelphia  for  10,000  tons  of  ice 
is  113  ft.  long,  78  ft.  wide,  60  ft.  high.  It  is  built  of  brick 
22  ins.  thick.  It  has  a  6-in.  reinforced  concrete  roof  carried  on 
girders.  The  insulation  of  the  walls  is  two  2  -in.  cork  boards 
held  in  place  with  cement  and  furnished  with  a  cement  plaster. 
The  floors  are  of  concrete  over  which  two  2  -in.  cork  boards 
are  laid  in  hot  asphalt  for  insulation.  The  ceiling  is  insulated 
with  3  ins.  cork  attached  by  Portland  cement  to  the  rein- 
forced concrete.  To  refrigerate  the  room,  15,000  ft.  of  2  -in. 
wrought  -iron  pipe  for  direct  expansion  are  used.  This  held 
the  room  at  22°  F.  in  the  warmest  weather.  To  handle  the 
ice,  plunger  elevators  with  oil  and  brine  as  the  working  fluid 
are  used. 

Ice  is  stored  in  these  houses  in  such  a  way  that  the  ice  will 
not  press  against  the  walls  and  the  blocks  should  be  so  placed 
that  they  will  make  a  stable  pile.  This  is  important. 

In  distributing  ice  it  is  well  to  use  a  map  of  the  city  and 
plan  routes  so  that  they  will  not  overlap.  Inspectors  must  be 
employed  to  watch  men  and  foremen  to  direct  their  work. 
To  guard  against  loss  of  money  ice  books  are  sold  by  drivers, 
who  are  held  responsible  for  them,  and  in  addition  the  amount 
of  ice  delivered  to  the  driver  and  the  amount  sold  by  him  must 
receive  a  daily  check.  It  is  best  to  use  a  single-horse  wagon 


ICE  MAKING  311 

in  charge  of  one  man,  since  where  two  men  are  on  the  wagon 
there  is  apt  to  be  talking,  drinking  and  more  waste  of  time. 
To  encourage  better  work  it  is  well  to  give  a  bonus. 

The  use  of  3 -ton  automobile  trucks  has  been  found  to  cut 
down  the  expenses  of  distribution  in  the  saving  of  time  in  reach- 
ing the  point  of  delivery.  This  is  especially  true  if  the  truck  is 
used  to  carry  ice  to  the  delivery  wagons.  In  using  automobile 
trucks  the  work  must  be  arranged  to  handle  ice  quickly.  There 
must  be  no  waiting,  as  the  fixed  charges  are  so  great  that  unless 
a  large  volume  of  work  is  done,  there  is  loss. 

Solicitation  of  trade  in  an  unobtrusive  way,  care  in  adjust- 
ing all  complaints  and  judicious  use  of  advertising  will  bring 
good  results.  It  is  absolutely  necessary  for  the  foreman  to  be 
acquainted  with  the  kind  of  service  given  to  consumers. 


CHAPTER  VIII 
OTHER    APPLICATIONS    OF    REFRIGERATION 

THE  use  of  refrigerating  in  various  industries  is  increasing. 
In  a  recent  list  of  applications  over  one  hundred  industries 
were  mentioned  in  which  refrigeration  played  an  important 
role.  A  few  of  these  will  be  described. 

In  the  manufacture  of  candy,  especially  chocolate-coated 
candy,  there  is  a  necessity  for  a  uniform  temperature  to  set 
the  chocolate  and  to  give  uniform  results.  Cool  air  is  blown 
into  the  rooms  to  keep  them  at  a  temperature  of  about  68°  F. 
as  chocolate  cannot  be  dipped  above  72°.  This  air  may 
either  enter  from  an  overhead  duct  at  50°  F.  and  be  used  to 
cool  the  room  enough  to  set  the  chocolate,  or  air  may  be  intro- 
duced into  setting  boxes  shown  in  Fig.  167.  The  chocolates 
are  placed  in  this  box  as  soon  as  one  plate  has  been  filled  with 
dipped  chocolates.  By  pressing  a  pedal  the  plates  in  the  box 
are  raised  to  admit  a  new  plate  from  beneath.  The  plates  are 
separated  by  distance  pieces  so  that  there  is  no  danger  of  the 
candies  being  mashed  by  contact.  Cool  air  is  introduced 
into  the  interior  of  the  box  from  the  duct  A  and  before  entering 
the  room  this  air  chills  the  candy,  setting  the  outer  coating. 
The  heat  which  it  removes  would  have  to  be  removed  in  any 
case  to  hold  the  room  at  65  or  68°,  and  so  this  apparatus  requires 
no  extra  refrigeration,  but  it  applies  the  cool  air  where  it  will 
do  the  greatest  good.  The  springs  B  B  hold  the  plates  in 
position.  This  is  employed  by  Harter  &  Co.  of  Ohio.  They 
have  a  6^-ton  machine,  cooling  a  bunker  5' X 5^X22',  using 
five  stands  of  2-in.  direct-expansion  pipes  12  ft.  high  and  20  ft. 
long  for  cooling.  A  52-in.  Buffalo  Forge  Fan  at  120  R.P.M. 
drives  the  air  through  a  24-in.  riser  to  i6-in.  pipes  with  3-in. 
branches  leading  to  the  cold  boxes.  This  saves  refrigeration, 

312 


OTHER  APPLICATIONS  OF  REFRIGERATION 


313 


as  the  room  need  not  be  cooled  to  such  a  low  temperature. 
In  the  plant  under  discussion  the  72  boxes,  each  caring  for 
150  Ibs.  of  chocolate  per  day,  required  6|  tons  while  it  would 
require  15  tons  for  the  ordinary  cool  room  according  to  the 
designer. 

At    the    Baker    Chocolate    Plant    six    loo-ton    absorption 
machines  are  used  to  supply  40,000  lin.ft.  of  2 -in.  galvanized 


FIG.  167. — Setting  Box  for  Chocolates. 

iron  pipe.  The  pipe  is  carried  throughout  the  plant  and 
bunkers  and  fans  are  placed  where  required. 

The  specific  heat  of  chocolate  is  given  as  0.9  by  Siebel, 
and  he  also  recommends  the  air  to  be  supplied  at  such  a  satura- 
tion that  the  relative  humidity  at  room  temperature  is  72%. 

The  heat  removed  in  this  case  is  similar  to  that  for  the 
blast  furnace  as  given  on  p.  324.  The  heat  from  the  walls 
of  the  buildings,  machinery,  lights,  persons  and  chocolate 
are  given  by  the  following: 


314  ELEMENTS   OF  REFRIGERATION 

Heat  leaking  through  walls  per  hour 

=  Qe=2KF(ta-tr).  .        .        .'.,        .        .        (l) 

Heat  from  machines  and  lights  per  hour 

=  g,=  2546H.P.+MQ,.     .     .  Y  .     .     (2) 

Heat  from  persons     =QP  =  N2Q' (3) 

Heat  from  chocolate  =  QC  =  MCX 0.9 X(/c  — /r).    »     .     ...     (4) 

K  =  coefficient  of  transmission  B.t.u.  per  deg.  per  sq.ft. 

per  hr.; 

F  =  square  feet  of  different  wall  areas; 
ta  =  outside  temperature ; 
tr  =  temperature  of  room ; 
HP  =  horse-power  of  machines; 
N  =  number  of  lights; 
Qg  =  heat  per  hour  per  light ; 
^2  =  number  of  persons; 
Qf  =  heat  per  person ; 
Mc  =  weight  of  chocolate  per  hour; 
tc  =  temperature  of  chocolate ; 
Q=Qe+Q,+QP+Qc. 

In  breweries  the  refrigerating  machine  is  of  great  value. 
Here  the  cooling  of  liquids  and  the  removal  of  the  heat  of  fer- 
mentation are  the  chief  applications. 

After  the  beer  is  brewed  the  solution,  known  now  as  wort, 
has  to  be  cooled  and  this  is  done  usually  in  a  Baudelot  cooler. 
The  Baudelot  cooler,  Fig.  168,  consists  of  a  series  of  horizontal 
pipes  formed  in  a  coil  through  which  cold  water  is  passed  and 
below  this  is  another  coil  in  which  liquid  ammonia  is  allowed 
to  boil  or  brine  or  cold  water  is  circulated.  Over  these  coils 
the  hot  wort  is  distributed.  The  wort  is  exposed  to  the  air 
and  will  take  up  oxygen,  thus  throwing  down  certain  matter 
in  solution,  and  also  there  is  some  solid  matter  thrown  out 
due  to  the  cooling.  The  room  in  which  this  occurs  is  usually 


OTHER  APPLICATIONS   OF  REFRIGERATION 


315 


enclosed  in  glass  or  copper  so  that  it  may  be  kept  clean  and 
free  from  foreign  bacteria,  which  would  produce  growths  not 
desired  in  the  fermentation.  This  cooling  is  intended  to 
reduce  the  temperature  to  prevent  bacterial  growth  should  any 
enter.  The  heat  removed  from  the  wort  depends  on  the  range 
of  temperature  and  the  specific  heat.  The  specific  heat  varies 
from  0.941  at  specific  gravity  1.032  to  0.861  at  specific  gravity 
1.0832,  with  a  negative  allowance  of  0.00015  for  each  degree 


Water  Outlet 


Upper  Portion  of 

Baudelot  cooled  by  Well 

or  Hydrant  Water 


FIG.  168. — Frick  Baudelot  Cooler  for  Beer  Wort. 

above  60°  F.  The  ordinary  drop  in  temperature  is  from  boil- 
ing to  110°  F.  in  a  storage  vat  and  then  the  wort  is  passed 
over  the  cooler  and  reduced  to  70°  F.  on  the  upper  coil  and  to 
from  40  to  50°  F.  on  the  lower  coil. 

The  beer  is  then  taken  to  fermenting  tubs  where  the  sugar, 
formed  in  the  operation  from  the  starchy  matter  by  the  diastase 
which  was  produced  by  the  change  of  barley  to  malt,  is  split 
up  into  CO2  and  alcohol  by  the  action  of  yeast  added  to  the 
wort  for  the  fermentation  process.  The  bacteria  of  the  yeast 


316 


ELEMENTS   OF  REFRIGERATION 


take   up   oxygen   and   also   nitrogen.      This    action    produces 
heat  and  as  a  rise  in  temperature  would  make  brewing  difficult 


FIG.  169. — Brewery  Plant  Showing  Cellars  and  Beer  Cooler,    After  De  la  Ver^ne. 

and  because  the  beer  is  to  be  reduced  gradually  in  temperature, 
it  is  necessary  to  cool  this  liquid  in  the  fermentation  tubs. 
This  is  done  by  circulating  cool  water  through  attemperating 


OTHER  APPLICATIONS  OF  REFRIGERATION 

pipes.  The  water  is  cooled  in  the^  attemperator  by  brine  or 
direct  expansion. 

After  this  the  beer  is  placed  in  storage  tubs  to  age  and 
finally  put  into  large  casks,  where  it  is  properly  finished  off. 
From  this  point  it  is  placed  in  kegs  for  shipment.  This  is 
known  as  racking. 

The  heat  removed  is  the  heat  leakage  through  the  walls, 
Qw;  the  heat  from  the  Baudelot  cooler,  ()&;  the  heat  from  the 
attemperator,  Qh  for  the  fermentation. 

The  heat  Qw  is  computed  in  the  manner  mentioned  before 
as  soon  as  the  temperatures  of  the  rooms  are  fixed.  The  fer- 
menting room  is  kept  at  42°  F.,  the  storage  rooms  at  33°  F., 
the  cask  rooms  at  36°  F.  and  the  racking  room  at  32°  F. 

The  heat  Qj,  is  given  by 


Qb  =  vol.  X62.5  Xsp.gr.  Xc(fe-//),       ....     (5) 

V  =  volume  of  wort  per  hour  in  cubic  feet; 
sp.gr.  =  specific  gravity  =  i  .05  mean; 
c  =  specific  heat  =  0.9  mean; 
th  =  temperature  from  brewing  =150  to  190°  F.  ; 
//=  temperature  to  tubs  =  40°  F. 

According    to    Siebel    the    heat   removed   in    fermentation 
is  given  by 

.......     (6) 


Mm  =  lbs.  of  maltose  split  up  per  hour  into  CCb  and  alcohol; 
330  =  B.t.u.  produced  by  the  breaking  up  of  i  Ib.  of  maltose. 

This  may  be  written  as 

Qf=6soXMa.   .  .  i  '.....     (7) 
Ma  =  lbs.  of  alcohol  produced  per  hour. 

This  usually  amounts  to  a  ton  of  refrigeration  per  40  to 
60  barrels  per  day.  The  total  refrigeration  of  the  brewery 
amounts,  according  to  Siebel,  to  a  ton  for  every  four  barrels 
per  day. 


318  ELEMENTS  OF  REFRIGERATION 

The  amount  of  surface  may  be  computed  by  the  methods 
of  Chapter  V.  Ordinarily  the  Baudelot  wort  coolers  are  made 
of  ten  2 -in.  pipes  16  ft.  long  for  fifteen  barrels  of  beer  per  hour 
to  cool  the  wort  from  70  to  40  by  the  use  of  direct  ammonia 
expansion.  With  brine  these  pipes  would  care  for  ten  to  twelve 
barrels  per  hour.  The  water  portion  of  the  cooler  to  cool  the 
wort  from  170  to  150  to  70  would  be  made  of  about  the  same 
number  of  pipes.  These  pipes  may  be  made  of  copper.  In 
the  at  tempera  tors,  coils  are  made  usually  of  a  coil  diameter 
of  two-thirds  the  tub  diameter.  Twenty-four  square  feet  is 
allowed  by  Siebel  per  100  barrels  of  wort.  The  rooms  for 
storage  of  hops  should  be  held  at  about  36°. 

The  cooling  of  air  is  one  of  the  modern  applications  of  refrig- 
eration. This  cooling  is  not  always  undertaken  to  obtain 
cool  air,  for  it  is  used  in  blast-furnace  work  where  warm  air  is 
needed,  but  in  this  case  the  cooling  is  to  reduce  the  moisture 
content  of  the  air.  Air  at  any  temperature  may  contain  a 
definite  quantity  of  moisture,  and  when  this  amount  is  present 
it  is  said  to  be  saturated.  The  amount  of  moisture  per  cubic 
foot  to  saturate  the  air  is  different  for  each  temperature.  It 
amounts  to  the  weight  of  i  cu.ft.  of  steam  at  that  temperature. 
The  air  and  moisture  are  really  the  mixture  of  several  gases 
and  a  vapor,  and  by  Dalton's  law  the  amount  of  each  constit- 
uent is  proportional  to  its  partial  pressure.  The  moisture 
or  steam  may  exert  the  pressure  corresponding  to  its  tempera- 
ture if  saturated,  and  with  this  pressure  the  weight  must  be  that 
required  to  produce  saturation.  If  the  air  is  not  saturated  the 
moisture  is  in  a  superheated  condition.  The  ratio  of  the  amount 
present  to  the  amount  required  to  saturate  the  air  is  known 
as  the  relative  humidity,  as  was  stated  on  p.  50.  The 
method  of  finding  the  relative  humidity  was  given  on  p.  175. 
From  Fig.  92  it  is  seen  that  air  of  relative  humidity  0.90  and 
of  temperature  85°  contains  13.7  grains  of  moisture  per  cubic 
foot.  If  this  air  is  cooled  to  82°  F.,  it  will  be  saturated,  and  if 
cooled  to  70°,  it  can  only  contain  8  grains  of  moisture.  So  that 
5.7  grains  must  be  thrown  out  of  suspension.  If  the  air  is 
cooled  to  36°  F.,  the  air  contains  only  2  grains  per  cubic  foot. 


OTHER  APPLICATIONS   OF  REFRIGERATIO,  319 

Thus  in  the  summer,  warm  air  may  be  passed  over  a  set  of 
coils  containing  cool  brine  and  when  this  air  is  delivered  into 
building  it  will  be  cooled  and  contain  less  moisture  than  in  its 
first  atmospheric  state. 

If  atmospheric  air  is  always  cooled  to  a  low  temperature, 
say  34°,  before  being  introduced  into  a  system,  the  air  will 
always  contain  the  same  amount  of  moisture  no  matter  what 
the  original  relative  humidity  of  the  warm  air  has  been.  It 
is  this  fact  which  has  been  applied  by  James  Gayley  to  the 
drying  of  blast-furnace  air. 

In  an  article  by  Gayley  in  the  Transactions  of  the  American 
Institute  of  Mining  Engineers,  he  points  out  that  in  the  Pitts- 
burg  district  the  variation  of  monthly  average  temperature  is 
from  31.7  to  76.2  during  the  year,  the  amount  of  moisture 
per  cubic  foot  in  these  two  cases  being  1.83  grains  and  5.60 
grains.  The  moisture  varies  from  0.56  to  8.78  grains,  changing 
by  large  amounts  even  in  one  day.  In  January  this  change 
was  from  0.56  grain  to  0.88  grain  on  the  same  day  and  from 
5.55  to  5.74  grains  on  a  day  in  July.  This  means  that  although 
the  ore,  and  coke  and  limestone  have  a  definite  composition 
within  10%  variation,  the  moisture  content  may  vary  100%. 
This  results  in  a  varying  amount  of  coke  to  care  for  the  dis- 
sociation of  the  moisture  and  a  difference  in  iron  produced. 
The  ordinary  furnace  uses  about  40,000  cu.ft.  of  air  per  minute 
and  this  contains  40  gallons  of  moisture  per  hour  for  every  grain. 
To  make  this  uniform  Gayley  proposed  to  cool  the  air  and  after 
trying  an  experimental  installation  he  applied  it  to  the  Isabella 
furnace  at  Etna,  Pa. 

In  this  plant  the  air  is  drawn  over  the  pipes  A ,  which  are 
supplied  with  brine.  These  pipes  are  arranged  in  three  coils  of 
twenty-five  2 -in.  pipes,  20  ft.  long.  The  three  coils  are  placed 
above  each  other  and  are  supplied  from  the  headers  C  and  dis- 
charged into  the  4-in.  headers  B.  The  coils  are  arranged  with 
staggered  2 -in.  pipes  and  there  are  sixty  coils  in  the  width  of 
the  bunker  room,  making  1 80  coils  of  twenty-five  pipes.  Cross- 
walls  divide  the  coils  into  four  sets.  There  are  90,000  lineal 
feet  of  pipe.  The  room  is  44  by  28  by  36  ft.  and  is  lined  with  2- 


320 


ELEMENTS  OF  REFRIGERATION 


FIG.  170.— Gayley  Air  Cooler. 


OTHER  APPLICATIONS  OF  REFRIGERATION  321 

in.  cork.  Air  is  drawn  in  by  fan  D  and  put  into  the  space  E 
under  1.2  oz.  pressure  to  care  for  the  frosting  of  the  pipes  and 
the  closing  of  the  air  passage.  The  fans  F  keep  the  air  evenly 
distributed  over  the  brine  coil.  The  air  finally  enters  the  6-ft. 
pipe  G  and  passes  to  the  blowing  engine  and  after  compression 
it  is  sent  to  the  hot-blast  stoves.  The  moisture  taken  out 
amounts  to  from  3000  to  5000  gallons  in  twenty-four  hours. 
Some  of  this  freezes  on  the  pipe  as  the  brine  enters  at  16°  F. 
and  leaves  at  33°.  The  defrosting  is  necessary  every  fourth 
day,  and  for  that  reason  the  brine  is  shut  off  of  one  of  the  four 
compartments  and  the  warm  water  from  the  ammonia  condenser 
is  passed  through  the  pipes  for  two  or  three  hours.  The  plant 
is  equipped  with  two  225-ton  compressors  requiring  460  H.P. 
There  are  thirty-seven  coils  in  the  atmospheric  ammonia  con- 
denser and  twenty  submerged  double-pipe  brine  coolers  placed 
in  a  brine  tank  7  ft.  6  in.  deep  and  22  it.  6  in.  long.  The  coolers 
are  made  of  twelve  double  pipes,  2  ins.  and  3  ins.  diameter  and 
are  17  ft.  12^  in.  long.  The  brine  in  the  tank  and  in  the  inner 
tube  is  cooled  by  the  ammonia  in  the  annular  space.  There  are 
40,000  gallons  of  CaCl2  brine  of  sp.gr.  1.2  in  the  system.  The 
brine  pump  and  fan  D  take  75  H.P.  The  total  power  needed 
is  535  H.P.,  while  the  three  air  compressors  use  3  times  671 
or  2013  H.P.  in  place  of  3  times  900  or  2700  H.P.,  as  was 
required  with  the  warm  air.  The  smaller  power  is  due  to  the 
smaller  volume  occupied  by  the  cooler  air  with  small  vapor 
pressure.  There  is  a  slight  saving  in  power,  but  the  main 
saving  is  in  the  amount  of  coke  used  and  in  the  uniformity  of 
operation;  358  tons  of  iron  were  made  with  2147  Ibs.  of  coke 
per  ton  originally  while  447  tons  per  day  were  made  with  1726 
Ibs.  of  coke  per  ton  after  the  installation  of  the  dry  blast. 
This  plant  was  started  in  August,  1904,  and  since  then  a  num- 
ber of  plants  have  been  installed.  In  general  the  output  may 
be  increased  by  10%  and  the  saving  in  coke  is  15%  when  this 
apparatus  is  used. 

Gayley  has  patented  a  scheme  of  passing  the  air  through 
two  coolers  in  series  and  using  cool  liquid  to  abstract  the  heat. 
In  this  case  air  is  blown  in  at  A  and  passes  up  through  grids  or 


322 


ELEMENTS  OF  REFRIGERATION 


baffles  over  which  a  cold  liquid  such  as  water  falls.  The  water 
is  pumped  by  the  centrifugal  pump  C  to  the  top  of  the  tower 
where  it  is  discharged  over  brine  or  direct-expansion  coils  D, 
which  cools  off  the  water  and  this  flows  down  over  the  grids. 


FIG.  171. — Gayley's  Two-stage  Air  Cooler. 


FIG.  172. — Air  Conditioning  Apparatus. 

The  cooling  of  air  for  churches,  hotels  and  auditoriums  or 

for  rooms  used  in  some  manufacturing  process  is  accomplished 
in  the  same  way.  In  this  case  the  air  is  freed  from  the  pre- 
cipitated moisture  by  first  passing  it  through  water  to  wash  it 
and  then  over  a  set  of  baffle  plates  arranged  as  in  A,  Fig.  172, 
called  eliminators  for  the  purpose  of  removing  the  moisture. 


OTHER  APPLICATIONS  OF  REFRIGERATION 


323 


The  figure  shows  the  arrangement  of  fan  B  and  bunker  C. 
The  bunker  C  contains  a  number  of  pipes  through  which  brine 
is  passed  to  cool  the  air  and  precipitate  the  moisture.  The 
eliminator  E  removes  the  moisture.  The  air  enters  at  F  and  is 
passed  through  tempering  coils  G  and  H  in  cold  weather.  The 
washers  /  consist  of  a  spray  through  which  the  air  passes.  This 
spray  washes  the  air,  taking  out  the  dirt  and  gases.  The  upper 
coils  C  serve  to  warm  part  of  the  air  if  necessary.  The  mixing 


FIG.  173. — Bunker  Room. 

dampers  at  K  are  used  to  get  a  proper  temperature  of  dis- 
charge. 

The  air  may  be  cooled  by  passing  it  through  a  spray  current 
of  cold  water  or  brine  or  the  air  may  be  passed  over  a  set  of 
revolving  discs  which  dip  into  a  cold-water  or  brine  tank,  and 
when  they  emerge  they  are  cool  and  prepared  to  cool  more  air. 

Fig.  173  illustrates  another  bunker  room  with  vertical  coils 
made  up  of  horizontal  pipes  and  return  bends.  These  are  con- 
nected to  two  mains.  The  coils  are  filled  with  brine. 


324  ELEMENTS  OF  REFRIGERATION 

At  the  Congress  Hotel  in  Chicago  a  3oo-ton  machine  is  used 
in  cooling  the  air  and  washing  it  for  proper  service. 

At  the  Luther  Memorial  Church  at  Orange,  Texas,  a  cooling 
plant  is  used  to  reduce  the  temperature  from  90  and  over  to  70°. 

The  City  Theatre  of  Rio  Janeiro  has  recently  been  finished. 
This  building  seats  1700  persons  with  200  on  the  stage.  Over 
50,000  cu.ft.  of  cold  air  per  minute  is  introduced  to  bunker, 
cooling  the  air  from  95°  to  68°.  This  requires  7^000,000  B.t.u. 
to  cool  the  air  and  2,340,000  to  condense  the  moisture.  The 
operation  is  carried  out  by  105  H.P.  motor  operating  an  S02 
compressor. 

The  problem  in  these  cases  is  to  find  the  amount  of  refrigera- 
tion. In  the  case  of  the  air  for  a  blast  furnace  the  known  data 
consist  of  the  amount  of  air  to  be  handled  per  minute,  Fi, 
the  maximum  temperature  T\<  the  relative  humidity  of  this 
pi  and  the  condition  to  which  it  must  be  changed  TV 

Weight  of  air  entering  =  (Bar~£lpl)Fl  =Ma    ....     (8) 

Bl  i 

Weight  of  moisture  entering  =  m\  pi  V\  =  M\      ....     (9) 

Volume  of  air  leaving  =  —-1  -  —=¥2       .....     (10) 

(Bar—  p2) 


Weight  of  moisture  leaving  ==W2F2  =  M2    .....     (n) 

Water  condensed  =  M\—  M  2  =MC     .......     (12) 

Energy  in  air  above  32  entering  =  o.24  Ma[Ti—4gi]=Qi  (13) 
Energy  in  moisture  above  32  entering  =  Mi  [ii]  =Q2  .  (14) 
Energy  in  air  above  32  leaving  =  o.24  Ma[T2  —  491]  =Qs  (15) 
Energy  in  moisture  above  32  leaving  =  M2fe]  =Q±  •  (16) 
Energy  in  condensed  moisture  =  Mcq2f  =  Q  5  .  ••  .  •  •  (17) 
Heat  removed  per  minute  =  6  =  Ci  +62  -(Qs  +64+65)  (18) 

mi  =  weight  of  i  cu.ft.  of  saturated  steam; 
Bar  =  Barometric  pressure  ; 
pi  =  pressure  of  steam  at  temperature  T\\ 


OTHER  APPLICATIONS  OF  REFRIGERATION  325 

Ti  =  absolute  temperature  of  entering  air; 
pi  =  relative  humidity; 

z'i  =  heat  content  of  moisture  at  entrance  (superheated); 
of  liquid. 


For  the  cooling  of  buildings  it  is  well  to  fix  the  temperature 
of  the  incoming  air  so  that  when  heated  to  the  temperature  of 
the  room  it  will  have  absorbed  the  heat  entering  into  the  room 
from  the  outside  and  from  processes  in  the  room.  If  the  various 
heat  losses  through  the  walls  be  found  from  the  K's  of  Chapter  V, 

Heat  from  walls  Qe  =  2KF(ta-tr)        .     .  .  (19) 

Heat  from  persons  QP  =  nQ'      -     •     •  .  •     •  •  (20) 

Heat  from  machines  and  lights  Qi  =  2$46XH-.P.+Qgni  .  (21) 
Now 


.02V(tr-te)  ....       (22) 

o.o2=B.t.u.  to  heat  i  cu.ft.  air  i°  F; 
V  =  volume  of  air  per  hour; 
ta  =  temperature  outside  air; 
tr  =  temperature  room  ; 
te  =  temperature  of  entering  air. 

V  is  fixed  by  the  number  of  persons  in  the  room.  In  some 
cases  this  is  made  1800  cu.ft.  per  hour  per  person.  This  may 
be  reduced  to  1200  cu.ft.  per  sitting  in  an  auditorium  where 
the  number  is  not  fixed.  The  value  of  V  is  given  by 

F=i2oo  n.    .     ........     (23) 

n  =  number  of  persons. 

Having  F,  te  may  be  found  and  the  problem  is  the  same  from 
this  point  as  the  original  problem  for  the  blast  furnace. 

Having  the  heat  removed  from  air  the  amount  of  surface 
required  is  given  by 

=^  .......     (24) 

A/i 

o£'7T 

A/2 


326  ELEMENTS  OF  REFRIGERATION 

F  =  bunker  surface  in  sq.ft; 
K  =  2.2\/wa  for  wet  surfaces; 
K  =  i  +  i.$\/Wa  for  dry  surfaces; 
Ah  =  difference  in  temperature  between  air  and  brine  at 

entrance  or  exit ; 

Ate  =  difference  in  temperature   between   air   and  brine  at 
exit  and  entrance. 

The  capacity  of  the  refrigerating  plant 

Tons  of  refrigeration  =  — ^—    ....     (25) 
199.2 

The  brine  cooler,  condenser  and  compressor  are  fixed  in  the 
same  manner  as  for  any  other  problem. 

This  method  may  be  used  for  the  air  needed  and  refrigera- 
tion for  a  chocolate  factory. 

Rinks.  The  use  of  expansion  coils  or  brine  coils  for  skating 
rinks  has  been  employed  in  many  places.  The  pipes  are  placed 
close  together,  using  about  0.8  sq.ft.  of  brine  pipe  or  0.6  sq.ft. 
of  direct-expansion  pipe  per  square  foot  of  rink.  The  heat 
to  be  removed  is  that  from  persons,  walls,  lights  and  fresh 
air. 

Ice  Cream.  The  making  of  ice  cream  has  become  a  refrig- 
eration problem  of  late  years.  The  use  of  cold  brine  for  the 
freezer  in  place  of  ice  and  salt  was  invented  about  1902. 

The  cream  when  first  received  is  stored  in  rooms  or  vats 
at  a  temperature  of  about  33°  F.  It  is  allowed  to  season  for 
about  twelve  hours  and  after  this  it  is  put  into  a  mixer  in  which 
the  various  ingredients  are  worked  together.  The  mixture 
is  now  taken  to  the  freezer,  which  may  be  of  the  batch  or  the 
continuous  form.  In  the  Fort  Atkinson  Horizontal  Freezer 
of  the  Creamery  Package  Co.,  Fig.  174,  a  seamless  German- 
silver  cylinder  with  a  scraper  revolving  against  it  has  a  brine 
coil  of  seamless  copper  pipe  around  it.  The  dasher  of  tinned 
bronze  is  caused  to  revolve  in  the  opposite  direction  from  the 
scraper.  The  whole  tank  is  properly  insulated.  Above  the 
cylinder  is  the  feed  tank  to  gauge  the  batch  accurately.  The 


OTHER  APPLICATIONS  OF  REFRIGERATION  327 

arrangement  at  the  end  of  the  feed  tank  permits  one  to  put 
fruit  in  at  this  point  without  placing  it  in  the  main  feed  tank. 
In  this  freezer  the  mixture  is  discharged  into  the  main  cyl- 
inder and  the  dasher  started.  The  cream  is  churned  and 
cooled,  and  as  the  heat  is  removed  there  is  a  swell  of  about 
69%  of  the  volume,  which  occurs  as  the  cream  passes  from  34° 


Tic.  174. — Fort  Atkinson  Freezer  of  Creamery  Package  Co. 

to  28^°  F.  It  depends  on  viscosity  and  the  rate  of  freezing. 
The  swell  is  due  to  air  being  introduced.  After  23^°  is  reached 
the  cream  becomes  brittle  and  the  dasher  will  beat  down  the 
cream.  The  cream  is  not  frozen  hard  in  the  freezer,  but  when 
the  swell  has  occurred  it  is  drawn  of!  while  it  is  still  thin  enough 
to  flow  slowly  and  is  put  into  cans  and  fixed  by  storage.  If 
the  mixture  is  at  34°  when  introduced  into  the  freezer  it  will 
be  necessary  to  operate  the  dasher  for  from  twelve  to  sixteen 


328  ELEMENTS  OF  REFRIGERATION 

minutes.  The  cream  is  now  put  in  a  hardening  room  at  o°  F., 
where  a  fan  keeps  the  air  in  circulation  and  thus  removes  the 
heat  to  harden  the  cream  in  six  or  eight  hours.  The  old  method 
of  submerging  the  can  in  brine  is  not  as  good  as  the  circulation 
method. 

The  freezers  are  made  of  various  sizes,  the  5 -gallon  size 
uses  f  to  i  H.P.  to  drive,  while  a  lo-gallon  one  takes  i|  to 
2  H.P.,  a  i5-gallon,  3,  and  a  25-gallon,  5  H.P. 

In  a  drug-store  plant  a  3-ton  Larsen  machine  with  5-H.P. 
motor  and  a  40-quart  freezer  with  2-H.P.  motor  was  placed 
in  a  space  of  2  by  8  ft.  and  a  dry  hardening  cabinet  3!  by  18 
by  3  ft.  with  a  cream  and  fruit  storage  10  by  12  by  8  ft.  were 
installed.  This  shows  what  a  small  space  is  absolutely  nec- 
essary. 

In  computing  the  heat  to  be  extracted  in  making  cream  the 
following  average  figures  may  be  used,  although  there  is  some' 
variation  from  the  various  flavors  of  cream. 

Specific  heat  of  milk o .  90 

Specific  heat  of  cream o .  68 

Specific  heat  of  liquid  ice  cream  o. 78 
Specific  heat  of  hard  ice  cream .   0.42 

Heat  of  fusion  ice  cream 80.0  B.t.u. 

Temperature  of  hard  cream. ...    10°  F. 
Temperature  of  soft  cream.  ...    16°  F. 

The  first  operation  is  the  cooling  from  temperature  of 
receipt,  or  if  pasteurizing  the  cooling  from  the  pasteurizing 
temperature  to  the  storage  temperature,  after  which  the  heat 
loss  from  the  storage  vat  is  cared  for.  The  next  cooling  is 
from  the  mixing  temperature  to  the  temperature  of  34°  F., 
and  then  the  heat  to  reduce  the  temperature  to  28°,  after  which 
it  is  drawn  out  and  stored.  Part  of  the  heat  of  fusion  is  taken 
out  in  the  freezer  and  part  in  the  hardening  room.  It  may 
be  assumed  that  one-half  of  the  heat  of  fusion  is  removed  in 
the  freezer. 

An  important  application  of  refrigeration  is  the  Poetsch 
process  for  sinking  shafts,  first  used  in  1885.  This  is  used 


OTHER  APPLICATIONS  OF  REFRIGERATION  329 

where  a  shaft  has  to  be  sunk  through  quicksand  or  where  a 
soft  wet  stratum  has  to  be  penetrated.  In  these  cases  the 
side  walls  of  the  shaft  would  be  forced  out  by  the  weight  above, 
and  to  prevent  this  sheet  piling  or  a  caisson  may  be  used,  or 
when  these  are  not  possible  the  ground  around  the  shaft  is 
frozen.  To  do  this  a  series  of  pipes  is  placed  in  holes  left 
by  a  drill.  This  casing  is  put  down  and  must  penetrate  the 
soft  stratum.  It  is  usually  put  down  after  a  drill  has  bored 
a  hole.  By  capping  the  end  of  the  pipe  and  forcing  water 
out  of  a  small  opening  in  the  end  of  another  pipe  on  one  side 
of  the  large  casing,  this  may  be  driven  through  the  soft,  sandy 
stratum  by  washing  the  sand  before  it.  After  the  casing  is 
put  down,  a  separate  pipe  is  put  inside  and  then  cold  brine 
is  pumped  down  and  allowed  to  pass  up  through  the  annular 
space  between  the  two  pipes,  removing  heat  from  the  damp 
earth,  and  freezing  it  into  a  solid  wall,  as  shown  by  dotted 
lines  in  Fig.  175.  In  the  Gobert  system  liquid  ammonia  is 
allowed  to  vaporize  in  a  large  casing,  removing  heat  from  the 
ground  around. 

To  compute  the  amount  of  heat  to  be  removed  the  tem- 
perature of  earth  must  be  found  and  its  weight  determined. 
The  specific  heat  is  0.2.  The  amount  of  water  to  be  frozen 
must  be  determined  by  drying  out  a  sample  of  the  earth  of 
known  volume  and  then  the  heat  abstracted  is  found  by 
using  the  general  values  of  specific  heats  of  water  and  ice  and 
the  heat  of  fusion  of  ice.  The  brine  will  freeze  the  earth 
for  about  i  yd.  from  the  pipe  with  the  ring  of  pipes  and  half 
that  distance  on  the  outside  with  o°  brine,  but  the  cooling 
will  extend  about  2  yds.  beyond.  This  cooled  layer  repre- 
sents the  heat  insulator  and  the  heat  carried  across  this  area 
represents  the  heat  which  must  be  supplied  to  keep  the  ring 
frozen.  The  heat  transmitted  from  zero  brine  amounts  to 
about  85  B.t.u.  per  sq.ft.  per  hr.,  according  to  Lorenz. 

The  time  taken  to  do  this  may  be  months,  and  for  that 
reason  a  non-conducting  house  should  be  built  around  the 
top  of  the  cooling  pipes  and  the  brine  pipes  must  be  carefully 
covered. 


330 


ELEMENTS  OF  REFRIGERATION 


IJlf 


g, 


OTHER  APPLICATIONS  OF  REFRIGERATION  331 

The  sections  of  the  heavy  outer  piping  are  joined  on  the 
inside,  while  the  inner  pipe  is  connected  by  ordinary  couplings. 

Another  use  for  refrigerating  machinery  is  the  cooling 
of  drinking  water.  This  has  been  demanded  in  hotels  by 
guests,  and  in  factories  it  has  been  required  by  the  manu- 
facturer on  account  of  the  effect  on  the  workman,  by  the 
workman  for  his  bodily  comfort,  and  by  the  legislature  in  laws 
for  the  bettering  of  working  conditions.  Of  course  this  may 
be  done  by  ice  placed  against  cooling  coils  and  ice  put  into  the 
old-fashioned  water  cooler  made  of  a  barrel  with  a  faucet, 
or  the  older  pail  and  dipper,  but  the  most  hygienic  method  is 
to  send  filtered  water  through  a  brine  or  direct-expansion 
water  cooler,  then  through  a  circuit  of  insulated  pipe  to  the 
cooler  again,  taking  off  sanitary  fountains  at  intervals. 

Dr.  Thomas  Darlington  states  that  about  3^  pints  of  water 
should  be  drunk  daily  to  care  for  water  given  off  from  the 
body.  This  water  is  necessary  to  aid  digestion,  to  carry  away 
waste  and  to  properly  regulate  the  actions  of  the  body.  The 
amount  of  water  required  varies  with  the  amount  of  muscular 
exercise  and  with  temperature.  He  states  that  the  temperature 
should  be  about  50°,  as  ice  water  is  apt  to  produce  cramp 
and  water  that  is  not  cool  is  so  unpalatable  that  persons  wiD 
not  drink  sufficient  of  it.  At  the  National  Tube  Works  water 
is  cooled  to  45°  F.  in  summer  and  to  50°  F.  in  winter.  The  water 
should  not  be  carried  in  lead  pipes,  to  avoid  the  danger  of  lead 
poisoning,  and  the  endeavor  should  be  made  to  filter  the  water 
to  remove  bacteria  and  sediment.  Filtration  makes  the  water 
attractive.  The  use  of  the  drinking-cup  common  to  all  men 
should  be  discontinued,  because  of  the  easy  transmission  of 
disease  thereby. 

A  large  drinking-water  cooling  system  has  been  installed 
by  the  National  Tube  Co.  in  Pittsburgh  at  their  Continental 
Works. 

The  plant  supplies  fountains  for  about  1000  men,  one  fountain 
being  used  for  each  thirty  men.  These  fountains  must  be  located 
at  convenient  points,  so  that  the  men  will  drink,  and  so  that 
the  drinking  will  not  consume  too  much  time.  The  distri- 


332 


ELEMENTS  OF  REFRIGERATION 


bution  is  made  through  15,000  ft.  of  ij-in.  galvanized  steel 
pipe  covered  with  ij  ins.  of  Nonpareil  cork.  The  temperature 
rises  about  7°  in  passing  the  circuit.  The  line  loops  down  at 
each  drinking-fountain,  Fig.  176,  as  shown  by  the  Nonpareil 
Cork  Co.  in  their  bulletin.  In  this  way  a  continuous  circuit 
of  cold  water  is  obtained  so  that  there  is  always  a  discharge 
of  cool  water  when  the  faucet  is  opened. 

The  water   from   the  city  filtration  plant  is  first   passed 
through  two  charcoal  and  gravel  filters  and  then  to  a  tank 


FIG.  176. — Drinking  Fountain. 

containing  direct  expansion  coils,  reducing  the  water  to  45°  in 
summer  and  52°  in  winter.  It  is  passed  by  means  of  a  pump 
through  three  lines  leading  to  all  parts  of  the  mill.  The  in- 
stallation uses  a  lo-ton  refrigerating  machine  for  this  plant. 
The  amount  of  water,  including  waste,  varies  from  about  i  gal. 
per  man  per  day  of  ten  hours  in  winter  to  2\  gallons  in  summer. 
The  cost  of  this  plant  was  $1.82  per  employee  per  year  against 
about  $5  per  man  when  ice  and  water  tanks  were  used 
with  the  loss  of  men's  time  from  sickness  due  to  cold  water. 
The  system  cost  about  $9000  to  install. 

In  planning  a  system,  \  gallon  per  hour  per  person  should 


OTHER  APPLICATIONS   OF  REFRIGERATION 


333 


be  allowed  to  cover  all  wastes  for  summer  use  with  hard  mus- 
cular labor.  In  less  active  work .  this  might  be  decreased  to 
i  or  TO  gallon.  In  carrying  this  water  a  study  must  be  made 
of  the  cost  of  pumping,  which  decreases  with  the  size  of  pipe; 
the  cost  of  heat  loss  through  the  insulation,  which  increases 
with  the  size  of  pipe;  and  the  yearly  cost  of  the  covering  and 
pipe  for  interest  depreciation,  taxes,  and  insurance,  which 


o- 


Various 
Mains 


-O 
-0 


•(-8-/J  Fountain 


pply 


Ammonia  Compressor 
Motor 


^Cork  Insulation 

FIG.  177. — Diagram  of  Drinking  Water  Plant. 


varies  with  the  size  of  pipe.  The  first  demands  a  large  pipe, 
the  second  and  third  a  small  pipe.  The  yearly  cost  of  several 
pipes  should  be  figured,  and  that  requiring  the  smallest  cost 
used.  The  Nonpareil  Co.  recommend  a  velocity  of  about 
3  ft.  per  second,  which  is  considered  in  Chapter  X.  This 
figure  may  be  used  as  a  starting-point.  A  low  velocity  pre- 
vents the  disturbance  of  any  sediment  in  the  pipe.  The  piping, 
of  course,  is  arranged  in  a  loop  from  the  cooling  tank  back  to 


334 


ELEMENTS  OF  REFRIGERATION 


the  tank.  The  fixtures  are  connected  to  the  main  flow  pipe, 
as  no  dead  ends  are  used.  Long  sweep  elbows  and  bends 
will  reduce  the  cost.  The  pipe  may  be  covered  by  special 
ice-water  pipe  covering  of  Nonpareil  cork  ij  ins.  thick  and 
specially  made  for  this  service. 

The  heat  required  for  such  a  system  is  made  up  of  two  parts : 
(a)  the  heat  to  cool  the  drinking  water  to  45°  F.  in  summer 
and  (b)  the  amount  to  care  for  the  radiation  from  the  pipe 


3.00 


U  16 

Pipe  size  in  inches 

FIG.  178.— Heat  Loss  per  Lineal  Foot  of  Pipe  per  Hour  per  Degree. 

covering.  This  latter  should  be  such  that  the  water  is  only 
warmed  7°  in  circulating  through  the  pipe.  This  temperature 
is  fixed  by  the  length  of  circuit  and  the  size  of  the  pipe.  The 
cork  covering  has  been  tested  as  shown  in  Chapter  VI,  and 
methods  of  that  chapter  may  be  used  to  compute  the  loss  or 
0.36  B.t.u.  may  be  taken  as  the  loss  for  i  in.  of  thickness  per 
square  foot  of  cork  surface  at  mean  circumference  per  hour 
per  degree  difference  in  temperature.  The  loss  from  plain 
pipe  is  0.8  B.t.u.  per  square  foot  per  hour  per  degree  dif- 


OTHER  APPLICATIONS   OF  REFRIGERATION  335 

ference.     The  heat  loss  is  given  in  curve  below  for  ice  water 
thickness  of  cork,  Fig.  178. 

Water  needed  per  hour 

,,      o. 25 X No.  of  men  at  one  time.    ,  f    N 

Mw= a-  -X62.4.          (26) 

7.48 

Heat  loss  from  pipe  in  any  circuit  =  H XL,     .     .     (27) 

#  =  heat  loss  per  foot  of  pipe  from  curve  for  assumed 

diam.  pipe; 
L  =  length  of  pipe. 

Heat  loss  in  water  flowing  for  5  °  rise  =  Me  X  5 .      .     (28) 

Hence  the  weight  of  water  circulated  to  care  for  heat  loss 
is  given  by 

:      '.  '  :       ^=Y-    -'•  V".  .  .  .   (29) 

The  area  to  allow  for  a  3  ft.  per  second  velocity  is  given  by 

pf«,+Mc  =  JFpX3X36ooX62.4  =  673,92oFP.    .     .     (30) 
Fp  =  interior  cross-sectional  area  of  pipe  in  square  feet. 

The  area  thus  found  must  check  with  that  assumed  for  (27) 
and  (29)  and  if  it  does  not  the  assumed  size  must  be  changed. 

Heat  loss  in  pipes  =  Qp  =  2HL  or  2 M c  X  5 .      .     .     (31) 
Heat  to  cool  water  entering  =  Qv,  =  Mto(qi  —  qo). 

g£  =  heat  of  liquid  at  temperature  of  city  supply  (80°); 
go  =  heat  of  liquid  at  outlet  temperature  (45°)  F. 

Heat  loss  from  tanks  =  Qt  =  FK(tr-to) .      .     .     .     (32) 

F  =  area  of  surface  of  tank ; 
K  =  coefficient  of  transmission; 
TT  =  temperature  of  room; 
To  =  temperature  of  water  in  tank. 


336 


ELEMENTS  OF  REFRIGERATION 


Heat  equal  to  work,  Qf  = 


778 


h  =  friction  drop  in  system. 

Tons  of  refrigeration  =  — 


60X199.2 


.  (33) 

(34) 


FIG.  179. — Methods  of  Covering  Pipes  and  Fittings  with  Nonpareil  Cork. 

Fig.  179  illustrates  the  section  of  cork  covering  of  various 
fittings  and  pipe,  and  Fig.  180  the  insulation  of  an  ice-water 
tank.  This  covering  is  made  of  boards  of  compressed  cork 


OTHER  APPLICATIONS   OF  REFRIGERATION 


337 


and  to  fit  around  pipes  the  cork  is  molded  to  form  and  where 
separated  sections  come  together,  a  waterproof  cement  is 
used  to  make  a  tight  joint.  The  sections  are  held  together 
with  four  copper-covered  steel  wires.  The  pipe  sectional 
coverings  are  put  in  so  that  the  half  sections  break  joints 
as  shown.  The  outer  surface  is  painted  with  an  asphaltic 
paint  and  cavities  are  filled  with  brine  putty  or  granulated 
cork  and  paraffin.  Fig.  181  illustrates  the  arrangement  of 
the  ice-water  plant  of  a  large  office  building  or  hotel.  The 


,7-2  "Cork  Hoards 


.Granulated  Cork 
or  Brine  Putty 

-Flanges 


-Wire 


4  Segments  of 
Cork  Board 


FIG.  1 80. — Armstrong  Covering  for  Water  Tank. 

centrifugal  pump,  A,  forces  the  water  through  the  closed  sys- 
tem. The  filter  B  is  used  to  supply  fresh  water  to  the  cooler 
C,  which  is  cooled  by  the  direct-expansion  coil  or  by  brine 
around  the  water  coil,  which  gives  up  its  heat  in  the  brine 
cooler.  A  closed  system  must  be  used  in  high  buildings  to 
balance  the  great  static  head,  so  that  the  pump  will  be  re- 
quired for  friction  only. 

In  chemical  works  the  use  of  refrigeration  to  remove  heat 
is  similar  to  that  for  water  cooling  or  chocolate  making.  There 
is  nothing  special  in  the  methods  of  calculation.  The  quan- 
tities required  are ; 


338 


ELEMENTS  OF  REFRIGERATION 


(a)  Heat  loss  through  walls. 

(b)  Heat  from  persons. 

(c)  Heat  from  motors. 

(d)  Heat  of  vaporization  to  condense  vapors  in  process. 

(e)  Heat  to  cool  liquids  in  process. 

(/)    Heat  of  fusion  to  solidify  liquids  in  process. 


FIG.  181.— Drinking  Water  System  in  Hotel  or  Office  Building. 

The  sum  of  these  quantitites  gives  the  heat  to  be  removed 
and  consequently  the  tonnage.  The  surface  to  abstract  this 
heat  is  then  found  by  fixing  the  temperatures  on  the  two  sides 
of  a  cooling  surface  and  obtaining  the  coefficient  of  heat  transfer. 
The  problem  is  similar  to  any  of  the  others. 


OTHER  APPLICATIONS  OF  REFRIGERATION 


339 


The  application  of  refrigeration  to  the  manufacturing  of 
photographic  supplies  and  to  oil  refining  has  demanded  large 
installation.  Another  use  is  to  prevent  chemical  action  by 
lowering  the  temperature  of  ammunition  holds  of  war  vessels. 

The  application  of  refrigeration  to  the  dairy  is  shown  in  a 
cut  from  the  Remington  Machine  Co.  in  Fig.  182.  In  this 
the  apparatus  used  in  a  dairy  is  shown  with  the  refrigerating 
machine  near  the  office.  The  direct-expansion  pipe  used  in  the 
cold-storage  room  and  in  the  cooler  is  not  shown.  The  cold- 


FIG.  182. — Complete  Dairy  Plant,  3o'X48'.     Remington  Machine  Co. 

storage  room   is  necessary  to  care  for  the  milk    and    cream 
properly. 

The  apparatus  of  the  Creamery  Package  Co.  shown  in 
Fig.  183  gives  the  requirements  of  the  modern  creamery.  The 
ammonia  compressor  draws  the  ammonia  from  the  brine 
cooler  placed  in  the  storage  room  or  above  it,  the  liquid  being 
delivered  to  the  cooler  from  the  condenser  by  an  expansion 
valve.  The  oil  trap  on  the  line  from  the  compressor  to  the 
condenser  is  marked  as  well  as  the  liquid  receiver  below  the 
condenser.  The  brine  pump  circulates  the  brine  from  the  brine 
tank  to  the  pasteurizer  and  wizard  back  to  the  cold-storage 


340 


ELEMENTS  OF  REFRIGERATION 


room.  The  milk  is  placed  in  the  receiving  vat  and  after  reaching 
the  proper  temperature  it  is  passed  to  the  separator  and  from 
this  the  cream  is  passed  to  the  pasteurizer  and  then  to  the  wizard 
ripener,  where  it  is  allowed  to  age  before  being  sent  to  the  churn. 
It  may  be  necessary  to  cool  the  cream  in  the  pasteurizer  or 
wizard,  and  for  that  reason  these  are  connected  by  pipes  to 
the  brine  system.  For  storage  of  butter,  cream  or  milk  a  cold- 
storage  room  is  used. 

Another  application  is  to  the  manufacture  of  liquid  air. 
It  is  known  that  the  throttling  action  of  perfect  gases  occurs 


FIG.  183. — A  Modern  Creamery.     Creamery  Package  Co. 

at  constant  temperature  because  the  heat  content,  which  remains 
constant  under  such  action,  is  a  function  of  the  temperature. 
However,  there  is  no  truly  perfect  gas  and  consequently  when 
gases  are  throttled  there  is  a  slight  drop  in  temperature  known 
as  the  Thompson- Joule  effect.  Tripler,  Hampson  and  Linde  used 
this  effect  to  obtain  low  temperatures.  Linde  machines  have 
given  the  best  results  and  are  shown  in  Fig.  184.  In  this  system 
a  two-stage  air  compressor  is  used.  One  stage  compresses 
atmospheric  air  to  240  Ibs.  per  square  inch  pressure  and  the  other 
stage  to  3000  Ibs.  per  square  inch.  The  atmospheric  air  is  com- 
pressed in  the  first  stage  and  sent  through  a  coil  around  the 
cylinder  A  placed  in  the  jacket  where  it  is  cooled  before  going 


OTHER  APPLICATIONS   OF  REFRIGERATION 


341 


to  the  second  stage.  The  air  there  passes  through  an  after  cooler 
around  the  second  stage  B, Rafter  which  it  enters  a  separator  C 
for  oil  and  moisture.  It  then  passes  through  a  coil  Z>,  where  it 
is  cooled  and  then  enters  the  inner  pipe  of  a  coil  of  three  pipes 
E.  In  this  coil  the  air  is  cooled  by  a  current  of  low-pressure 
air  which  has  been  cooled  to  a  low  temperature,  so  that  when 
the  air  reaches  the  end  F  of  the  coil  it  is  quite  cold.  It  is  here 
allowed  to  expand  from  3000  to  240  Ibs.  by  the  valve  G  and  as 
a  result  its  temperature  should  be  lowered  203°  C. 


FIG.  184. — Linde  Liquid  Air  Machine. 

The  incoming  air  could  be  cooled  to  136.5°  when  the  throttling 
is  from  3000  Ibs.  to  240  Ibs.  per  square  inch  absolute. 


Aooo      240 

i  -/2  =  0.276  —  - 

1   \i4-7     i4'-7 


273 
—  = 


203 


(35) 


Of  course  the  air  could  not  drop  so  much  and  the  heat 
required  to  keep  the  heat  content  constant  means  that  part 
of  the  air  must  be  liquefied.  Part  of  this  air  at  240  Ibs.  is 
throttled  to  14.7  Ibs.  by  H  and  is  then  sent  out  to  the  atmos- 
phere through  the  outer  annular  space  to  7.  The  amount  left 
between  G  and  H  is  four-fifths  of  the  total  air,  and  this  is  sent 

*  Equation  for  Thompson- Joule  effect. 


342  ELEMENTS   OF  REFRIGERATION 

back  through  the  first  annular  ring.  This  air  is  at  240  Ibs. 
per  square  inch  and  is  taken  to  the  intermediate  receiver  of 
the  compressor.  This  air  is  cooled  in  the  coil  surrounding  the 
cylinder  B  and  the  coil  around  D  removes  some  of  the  heat 
from  the  high-pressure  gas. 

When  the  machine  is  started  the  air  leaving  at  G  and  H 
may  not  liquefy,  although  there  is  a  drop  of  50°  C.  and  this  cools 
the  next  lot  of  gas,  which  of  course  drops  to  a  lower  temperature 
and  soon  liquid  air  appears. 

In  this  apparatus  the  liquid  air  which  forms  is  collected  in 
the  vessel  L.  The  air  is  at  a  low  temperature,  corresponding 
to  the  boiling  temperature  at  atmospheric  pressure.  These  low 
temperatures  may  be  used  for  any  abstraction  of  heat  to  tem- 
perature at  a  little  above  that  of  the  air,  the  liquid  boiling 
away  as  the  heat  is  abstracted. 


CHAPTER   IX 

COSTS    OF    INSTALLATION    AND   OPERATION   TESTS 

THE  cost  of  equipment,  supplies,  fuel  and  labor  will  vary 
from  time  to  time  and  the  figures  given  in  this  chapter  have 
been  collected,  through  the  kindness  of  many  manufacturers, 
as  a  guide  to  the  student  in  determining  cost  of  apparatus 
and  manufacture.  They  should  be  used  as  guides  only  on  ac- 
count of  the  fluctuation  in  prices.  They  were  compiled  in  1916, 
but  prices  in  use  before  the  outbreak  of  the  European  war 
were  employed. 

Land.  The  cost  of  land  will  vary  with  the  location  in  a 
city  and  with  the  city.  In  the  outskirts  of  small  towns  it  may 
be  worth  from  i  cent  per  square  foot  or  $400  an  acre  to  5 
cents  a  square  foot  or  $2000  an  acre.  In  a  small  city  this  will 
vary  from  $1000  an  acre  to  $12,000  an  acre,  near  the  railroad. 
This  latter  price  is  about  30  cents  per  square  foot.  In  the 
business  districts  of  large  cities  $25  per  square  foot  has  been 
paid. 

Buildings.  The  cost  of  buildings  will  vary  with  the  type 
of  structure.  There  are  a  number  of  variable  units  which 
enter  into  the  problem  and  unit  costs  of  various  parts  of  a  struc- 
ture are  given.  For  preliminary  estimating  the  total  cubic 
contents  of  the  building,  including  cellar,  may  be  found  and 
then  a  unit  cost  selected  from  the  table  below  is  used  to  find 
the  total  cost.  This  is  known  as  "  cubing  the  building." 

.     COST  OF  BUILDING  PER  CUBIC  FOOT,  UNINSULATED 

Office  Buildings 

Frame 10  cts.  per  cu.ft.,  $1.00  per  sq.ft.  floor 

Brick  and  timber 13  1.25          ' ' 

Brick  and  steel 20  "  i .  75  " 

Reinforced  concrete 20  ' '  i .  75          " 

343 


344  ELEMENTS   OF  REFRIGERATION 

Storehouses 

Frame 6  cts.  per  cu.ft.,  $0.60  per  sq.ft.  floor 

Brick  and  timber 8  0.80 

Brick  and  steel 12  1.20 

Reinforged  concrete 12  1.20 

Power  Houses 

Frame 9  cts.  per  cu.ft.,  $0.90  per  sq.ft.  floor 

Brick  and  timber n  i.io 

Brick  and  steel 15  1.50 

Reinforced  concrete 15  1.50 

UNIT  PRICES  OF  BUILDING  ELEMENTS 

Excavation  and  Hauling 

Earth $   .  30  to    .  50  per  cu.yd. 

Rock i .  50  to  3 .  oo        ' ' 

Masonry 

Ordinary  brick 33  cts.  per  cu.ft.,  $8 .91  per  cu.yd. 

Rubble  stone 22                             6.00        " 

1:3:5  concrete 22                             6.00        " 

Reinforced  concrete 37            "             10 . oo        " 

Concrete  forms $3 .  oo  to  $5 .  oo  per  cu.yd. 

Brick  chimneys $13 .  oo  per  cu.yd. 

Fireproofing 20  cts.  per  sq.ft. 

Steel  Work 5  cts.  per  Ib. 

Lumber 

Heavy  Georgia  pine  timber $50.00  per  M  bd.  measure 

Georgia  pine  joist 40 .  oo                " 

Spruce  joist 34  •  oo                " 

Yellow  pine  boards 25 .  oo                " 

Spruce  boards 32. oo 

Ship  lap,  pine  or  spruce 26 .  oo                l ' 

Clapboards,  pine  or  spruce 32 . oo                " 

Cypress  boards 60 .  oo 

Yellow  pine  flooring,  vertical  grain,  £" 50.00  per  M 

Oak  flooring,  |" 70.00       " 

Maple  flooring 50 .  oo       " 

Shingles 2 . 50  to  5 .  oo  per  M 

Lath  (10  cts.  per  sq.yd.  wall) 4-65 

Studding,  3/'X4//  and  2"X4"  spruce 30.00  per  M 

Carpentering 
Allow  from  one-half  to  full  value  of  lumber  for  labor. 

Plastering 
Lime  and  hair 30  cts.  per  sq.yd. 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     345 

Floors  and  Roadways 

Asphalt  facing,  i" $i .  20  per  sq.yd. 

Concrete  sidewalks , $i .  80 

Concrete  roadway,  6" o .  70 

Macadam  roadway,  6" i  .00 

Brick  roadway 1.75 

Asphalt  roadway 3 . 50 

Concrete  fireproof  floors 18.00  per cu.yd. 

o .  60  per  cu.ft. 

Partitions 

Tiles  4"  thick  (i2"Xi2") 5i  cts.  per  sq.ft. 

8"  thick  (i2"Xi2") 10 

Labor  equals  cost  of  tile. 

Roofing 

Copper  roofing $25 .  oo  per  square  (100  sq.ft.) 

Slate  roofing $10 .00  " 

Tin  roofing 7 . 50  ' ' 

Slag  roofing 4 .  oo  " 

Book  tiles,  2" 07^  per  sq.ft. 

3" _ 08^        " 

Rain  conductors,  tin .12  per  ft. 

Copper .35     " 

Mill  Work 

Windows  with  sash  and  trim $8.00  to    $12 .00 

Outer  doors  and  frames 25 .  oo  to    100 .  oo 

Inner  doors  and  trim S.ooto      15. oo 

Base  boards 08  to    .16  per  lin.ft. 

Stairs 2 .  oo  to  10 .  oo  per  step 

Plumbing 

Water-closets $25 .  oo  per  unit 

Wash  basins $12 .00  per  basin 

Urinals 25 .00  per  stall 

Soil  pipe  (iron) 25  per  ft. 

Painting 

White  lead  and  oil 38  cts.  per  sq.yd.  for  3  coats 

Mineral  paint 24  "  " 

Asphaltum 35  ' '  " 

Whitewash 15  "  "     2     " 

Insulation 

Building  paper . . . . $2 .00  to  $8.00  per  roll  of  500  sq.ft. 

Asbestos,  loose . . . .' $1.25  to  $2.25  per  100  Ibs.,  filling  3  cu.ft. 

85%  magnesia $2.00  to  $3.00  per    60  Ibs.,  filling  3  cu.ft. 

Hairfelt  i"  thick 06  per  sq.  ft. 


346 


ELEMENTS  OF  REFRIGERATION 


Cork  boards:    Walls.    2"  thick  on  brick  or  wood  walls  with  cement  finish,  erected. 

25  cts.  per  sq.ft. 

2-2"  thicknesses,  40  cts.  per  sq.ft 
1-3"         "  30 

2-3"         "  60 

Add  8  cts.  for  cork  partition  with  two  sides  plastered. 
Floors.  2"  cork  board  in  asphalt,  3"  concrete  top  on  asphalt  cov- 
ering with  i"  surface,  34  cts.  per  sq.ft.     Same  with  3" 
cork,  40  cts.  per  sq.ft.     2-2"  layers,  50  cts.  2-3"  layers 
60  cts. 

Ceilings.    2"of  cork  on  concrete  or  wood  and  \"  cement  plaster,  27  cts. 
per  sq.ft.;  3"  cork,  32  cts.;  2-2",  43  cts;  and  2-3",  64  cts. 
Granulated  cork:     Unscreened  granulated  cork .  .  $70 .  oo  per  ton. 
^o  rescreened  granulated  cork ...     60.00     " 

•/o  granulated  cork 35 .  oo     " 

Coarse  regranulated  cork 45 .  oo     ' 

Fine  regranulated  cork 35-°o    " 


PIPE  COVERING    CORK  (NET) 


COST  PER  FOOT. 

COST  PER  FITTING. 

Size 
Pipe. 

Standard 
Brine 

Ice 
Water 

Cold 
Water 

Standard  Screwed 
Fittings. 

Standard  Flanged 
Fittings. 

Thick- 

Thick- 

Thick- 

1 

ness. 

ness. 

ness. 

Ells. 

Tees. 

Valves. 

Ells. 

Tees. 

Valves. 

Flanges. 

} 

$0.34 
•  43 

$0.27 
•  34 

$0.24 
•  30 

$0.46 

•54 

$0.50 
.63 

$0.54 
•  7i 

$2  .  2O 
2.20 

$2.60 
2.60 

$3-05 
3-05 

$0.76 
•  76 

i 

•  54 

•43 

•  39 

•  7i 

•  79 

.87 

3.05 

3-50 

3-90 

•  96 

ij 

.63 

•  50 

•45 

•  79 

.88 

.96 

3-50 

3-85 

4-30 

I  .  IO 

it' 

.71 

•  57 

•  Si 

.88 

.96 

i  .04 

3-90 

4-30 

4.90 

1,24 

2 

.80 

.64 

•  57 

.96 

i.  08 

1.23 

4-35 

4.90 

5-50 

1.36 

4 

I  .  21 

•  97 

.87 

i.  60 

1.79 

2.08 

7-30 

8.15 

9.  20 

2.05 

6 

1.70 

1.34 

2.00 

2.30 

3-02 

II  .  IO 

12.05 

13-50 

3.05 

10 

3.40 

2.70 

3.45 

21  .30 

42  .00 

20.85 

28.90 

41.90 

5.60 

16 

4-30 

3-18 

23.55 

32.30 

39-75 

55.90 

71  .00 

6.80 

PIPE  COVERING,  85%  MAGNESIA  (NET) 


COST  PER  FOOT. 

COST  PER  FITTING. 

Size 

Pipe. 

ij  Ins.  Thick. 

2  Ins.  Thick. 

Elbows. 

Tees. 

Valves. 

I 

$0.13 

$0.21 

$0.08 

$0.09 

$0.14 

2 

.16 

•25 

.09 

.11 

•15 

3 

.19 

.29 

.  12 

•14 

.16 

4 

.22 

•34 

•15 

.16 

.38 

6 

.28 

•43 

•33 

.40 

.70 

IO 

.42 

.60 

.90 

.     I-  IS 

i-55 

COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     347 

Machinery  Costs.  These  costs  are  made  up  of  various  items 
listed  in  the  tables  which  follow.  The  prices  represent  average 
cost  prices  with  discounts  taken  off.  The  items  are  for  indi- 
vidual machines,  but  for  complete  equipment  Mr.  Thomas 
Shipley  gives  the  following  as  a  guide  for  the  cost  of  ice  plants 
per  ton  of  ice-making  capacity  when  they  are  at  least  of  50 
tons  capacity. 

Compression  can  system $550  per  ton 

Compression  block  system $$(? 

Compression  plate  system  (direct  expansion) 800 

Compression  plate  system  (brine) 1000 

Absorption  can  system 500 

The  yield  of  these  plants  will  be  7^  to  10  tons  of  ice  per 
ton  of  coal  in  distilled-water  can  plants,  10  to  35  tons  in  raw- 
water  can  plants,  and  10  to  15  tons  in  plate  plants. 

Refrigerating  Plants.     Cost  of  Mechanical  Equipment: 

Plants  of  50  tons  and  over $150  to  $300  per  ton  of  refrigeration 

Plants  of  8  to  20  tons 250 

Plants  of  3  to  8  tons 300 

Plants  of  i  to  3  tons 250 

Efficiency  of  Apparatus: 

Boilers 60  to  80% 

Producers 60  to  80 

Steam  engines  (indicated  thermal) : 
Non-condensing: 

Simple 6% 

Compound 10 

Unaflow. ii 

Corliss 9 

Condensing: 

Compound 20% 

Mechanical  efficiency  of  engines. 85  to  95% 

Steam  turbines  (overall  thermal) : 

Non-condensing 6% 

Condensing,  small 8 

Condensing,  medium 10 

Condensing,  large 21 

Gas  and  oil  engines: 

Indicated  thermal  efficiency 25  to  35% 

Mechanical  efficiency 85 

Compressors: 

Mechanical  efficiency 85  to  95% 

Volumetric  efficiency 88 


348 


ELEMENTS  OF  REFRIGERATION 


Fuels: 

Crude  Oil: 

Heating  value  per  Ib IQ,OOO  to  20,000  B.t.u. 

Weight  per  cu.ft 50  Ibs. 

Cost  per  barrel  of  42  gallons $i .  50 

Gasoline: 

Heating  value  per  Ib 20,500  B.t.u. 

Weight  per  cu.ft 50  Ibs. 

Cost  per  gallon 20  to  30  cts. 

Bituminous  coal: 

Heating  value  per  Ib 13,800  B.t.u. 

Weight  per  cu.ft.,  loose 50  Ibs. 

Cost  per  ton  of  2240  Ibs.  at  mine $i .  55 

Cost  of  freight  for  300  miles i .  90 

Anthracite  pea  coal: 

Heating  value  per  Ib 13,400  B.t.u.    . 

Weight  per  cu.ft.,  loose 56  Ibs. 

Cost  per  ton  of  2240  at  mine $2 . 65 

Cost  of  freight,  200  miles i .  60 

Anthracite  buckwheat  coal : 

Heating  value  per  Ib 12,800  B.t.u. 

Weight  per  cu.ft 56  Ibs. 

Cost  per  ton  of  2240  Ibs.  at  mines $i  .85 

Cost  of  freight,  200  miles i .  50 


BOILERS  AND  SUPERHEATERS.     EFFICIENCY  65  TO  80% 
COST  or  BOILERS 


BOILER  HORSE-POWER  (10  SQ.FT.  PER  H.P.). 


50 

100 

200 

300 

400 

500 

Return  tubular 

$  760 

$1120 

$2OOO 

$2800 

Water  tube 

I  ^OO 

2300 

3600 

4700 

$5700 

$7500 

Superheaters,  10  to  15%  of 
boiler  surface  for  100  to 
120°  F  superheat 

600 

600 

IOOO 

1300 

1500 

1600 

PRODUCERS.     EFFICIENCY  60  TO  80% 
COST  OF  PRODUCERS 


H.P. 

Cost. 


80 
$1600 


IOO 

$1800 


150 

$2200 


200 

$2500 


250 
$2800 


300       400 
$3200     $3800 


Producers  are  based  on  1.2  Ibs.  of  coal  per  hr.  per  H.P. 
to  burn  9.4  to  10  Ibs.  of  coal  per  sq.ft.  per  hour. 


Grate  areas  of  size 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     349 

ENGINES  AND  TURBINES 

Steam  consumption  of  engines  per  I.H.P.  hour: 

Simple  non-condensing 24  to  40  Ibs. 

Compound  non-condensing 2 1  to  36 

Compound  condensing 14  to  20 


COSTS 
CORLISS  ENGINES,  SIMPLE  (100  Ibs.  per  sq.in.  gauge) 


Indicated  H.  P.. 
Size 

20 
8X18 

40 
10X30 

70 
12X30 

100 

14X36 

150 
16X36 

200 
18X42 

300 
22X42 

Cost 

$1000 

$1200 

$1500 

$1900 

$2150 

$27OO 

SltjOO 

CORLISS  ENGINES,  COMPOUND  (125  Ibs.  per  sq.in.  gauge) 


Indicated  horse-power  
Size 

IOO 

10  and  18X36 

600 
20  and  36X42 

1000 

26  and  50X48 

Cost             

Tandem 

$3000 

Cross 

$10,000 

Cross 

$2O,COO 

HIGH-SPEED  ENGINES 


Indicated  horse-power.  .  . 
Size  

47  to  107 
10X10 

75  to  162 
12X12 

87  to  189 
13X12 

107  to  240 
14X14 

185  to  390 
18X18 

Cost  belted 

$7  5  5 

$080 

$1015 

$1260 

$2510 

Cost,  direct  connected  .  . 

IO2O 

1270 

1375 

1617 

3000 

Piston  speed  from  550  to  650  ft.  per  min. 
Steam  pressure,  80  to  150  Ibs.  per  sq.in.  gauge. 
Mechanical  efficiencies,  85  to  95%. 
Steam  consumption,  29  to  35  Ibs.  per  I.H.P.  hour. 


TURBO-GENERATORS 


Capacity  in  K.W. 
Cost  

25  D.C. 

$l-27tr 

loo  D.C. 

$3800 

150  D.C. 

$(T2OO 

200  D.C. 

$6200 

loo  A.C. 

$4100 

200  A.C. 

$<coo 

Steam  consumption  40  Ibs.  per  K.W.  hr.  in  small  sizes  to  26  Ibs.  per  K.W.  far. 
in  large  sizes.     Both  condensing. 


350 


ELEMENTS  OF  REFRIGERATION 
GAS,  GASOLINE,  OIL  OR  PRODUCER  ENGINES 


Indicated  horse-power.  . 

5 

10 

25 

5o 

I  GO 

2OO 

300 

Cost  of  gas  or  gasoline 

engine  

$210 

$380 

$770 

$1500 

Cost  of  fuel-  oil  engine. 

1900 

3100 

4600 

6800 

06OO 

Cost  of  engine  and  suc- 

tion producer 

1800 

2800 

47OO 

7OOO 

0800 

Add  15%  for  freight  and  erection  of  engine  and  producer. 

ELECTRIC  GENERATORS  (B.C.) 
Efficiency  90  to  95% 


Capacity  in  K.W. 

2$ 

5° 

7^ 

IOO 

I^O 

2OO 

Cost  belted  

$4  CO 

$600 

$1000 

$1000 

$1500 

$22OO 

Cost  direct  connected 

6zo 

87<> 

II^O 

1400 

18^0 

24.OO 

ELECTRIC  MOTORS  (B.C.) 

Efficiency  85  to  95% 


Horse-power  

7! 

I  C 

25 

5° 

75 

IOO 

150 

200 

Cost  

$213 

$290 

$450 

$605 

$7i5 

$1225 

$1290 

$2400 

SWITCHBOARBS 
SWITCHBOARDS  FOR  B.C.  GENERATORS 


Capacity  in  amperes 

12< 

2^O 

37C 

=500 

75° 

IOOO 

Cost  

$69 

$78 

$78 

$87 

$155 

$175 

Voltmeter,  ammeter,  rheostat,  main  switch  and  fuses. 


SWITCHBOARDS  FOR  A.C.  GENERATORS 

Capacity  in  amperes 100  "  200 

Cost $125  $150 

(Ammeter,  voltmeter,  exciter  field  switch,  exciter  and    generator    rheostat 
mounting,   triple  pole  main  switch  and  fuse.) 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     351 


AMMONIA  COMPRESSORS 

Mechanical  Efficiency  85  to  95% 


Capacity  in  tons  of  ice  
2-ton  refrigeration  =  i  ton  ice. 

2 

5 

10 

25 

50 

$3400 
5000 
6500 

IOO 

2OO 

Cost  of  compressor  (belt  drive)  
Cost  of  compressor  and  simple  engine  .... 
Cost  of  compressor  and  compound  engine. 

$550 
730 

$700 
1150 

$1150 
1800 

$1850 
2675 
4550 

$8,700 
10,670 
13,750 

$17,950 

21,160 
27,500 

AIR  COMPRESSORS 

Mechanical  efficiency  of  compressor  and  motor  85%. 
Efficiency  of  system  from  compressor  motor  to  air  motor  40%. 


Free  air  in  cu.ft.  per  min  
Diam  steam  cylinder  inches 

55 
6 

no 
8 

250 

IO 

350 

I  2 

Diam  air  cylinder  inches    . 

7 

Q 

12 

14 

Stroke,  inches.               

6 

8 

IO 

12 

Price  of  engine  compressor,  governor  and 
unloader 

$^2O 

$700 

$1080 

$1500 

Price  of  belt-driven  compressor  with  un- 
loader 

270 

400 

64O 

O4O 

Max.  pressure  by  gauge  in  Ibs.  per  sq.in.  . 

IOO 

IOO 

IOO 

IOO 

PUMPS 

Direct  acting  for  boiler  feed,  brine,  or  aqua  ammonia. 

Mechanical  efficiency,  75%. 

Steam  per  I.H.P.  hour,  100  to  400  Ibs. 


Gallons  brine  per  minute  
Size  in  inches  for  brine  (Simplex)  . 
Cost  

IOO 

6X6X7 

$170 

250 
8X8X13 

$260 

500 
12X12X20 

$?7O 

IOOO 

$870 

Weight  in  Ibs 

800 

1660 

4OOO 

8650 

Boiler  horse-power  

GO 

IOO 

42^ 

IOOO 

Size    in    inches    for    boiler    feed 
(Simplex). 

5X2|X6 

e  V^iV? 

6X4X12 

.9X6X13 

Cost  

$00 

$IIO 

$1  SO 

$2^0 

CENTRIFUGAL  PUMPS 
Mechanical  Efficiency  60% 


Gallons  per  minute  

IOO 

2  so 

soo 

IOCC 

Speed  

1800 

1800 

2OOO 

1600 

Horse-power 

7    ^ 

J  C 

2  S 

CQ 

Weight  in  Ibs  

CQO 

72C 

ooo 

i  soo 

Cost  without  motor 

$180 

$190 

$27O 

$330 

Pressure  in  Ibs.  per  sq.in  

IOO 

IOO 

IOO 

IOO 

352 


ELEMENTS  OF  REFRIGERATION 


AIR  LIFT  PUMP 

Mechanical  Efficiency  40% 

FAN  BLOWERS 

Mechanical  Efficiency  60% 


Capacity  at  i  oz.  in 
cu  ft  per  min 

2OOO 

4OOO 

8OOO 

16  ooo 

26  ooo 

Diam.  wheel  in  inches. 
Cost   

15 

$I2O 

21 
$IOO 

30 

$27O 

4i 
$400 

53 
$600 

64 

$800 

:>4,uuu 

$11  <o 

&l62< 

BELTING 

Efficiency  of  Transmission  93  to  97% 

Cost  per  inch  of  width,  single  thickness 8|  cts.  sq.ft. 

Cost  per  inch  of  width,  double  thickness 17  cts.  per  ft. 

Ammonia  Condensers,  Coils  and  Fittings.  Allow  5  to 
10°  F.  difference  in  temperature  between  water  and  vapor  in 
saturated  portion  of  condenser.  Use  2-in.  pipe  for  single-pipe 
condensers,  20  ft.  long,  and  24  pipes  high  in  large  stands,  i^-in. 
pipe  may  be  used.  3-in.  and  2-in.  pipe  are  used  in  double-pipe 
condensers.  Use  K  =  50  for  superheated  portion  of  condenser, 
100  to  200  for  portion  in  which  there  is  liquid  on  each  side  in 
double-pipe  work;  60  is  the  value  used  in  ordinary  single  pipe 
type  of  condenser.  In  the  Block  and  Shipley  forms  of  con- 
denser ^=200.  About  18  sq.ft.  of  surface  is  allowed  per  ton 
of  capacity  and  it  may  be  reduced  to  8  sq.ft.  where  liquid 
ammonia  is  on  the  inner  surface. 

Cost  of  double-pipe  condensers  of  i^-  and  2-in.  pipes  20  ft- 
long  is  given  by: 

Cost  per  stand  =  $5+$i5Xnumber  of  pipes  high. 

For  2  and  3-in.  pipes,  20  feet  long: 

Cost  per  stand  =  $30+$! 5  X number  of  pipes  high. 

Cost  of  Condensers  with  pan  is  given  below: 


Capacity  in  tons  of  ice  

2 

c 

10 

2C 

ro 

IOO 

2OO 

Cost  for  single-pipe  condenser.  .  .  . 

$160 

$220 

$400 

$900 

$1700 

$3250 

$6550 

Cost  for  double-pipe  condenser.  .  . 

100 

150 

250 

450 

850 

1700 

3ISO 

COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     353 


DE  LA  VERGNE  "  STANDARD  COUNTER-CURRENT  ATMOSPHERIC  AMMONIA  CON- 
DENSERS (Fie.  73) 


Number 
of  Stands. 

Sq.ft.  of 
Cooling 
Surface. 

Capacity  — 
Tons  of  Ice 
Melted  per 
24  Hours. 

Length 
Over  All. 

Width 
Over  All. 

Sq.ft.  of 
Floor  Space. 

I 

222 

iH. 

23'  6" 

4'o" 

94 

2 

444 

25 

23'  6" 

6'  o" 

141 

4 

888 

SQ 

23'  6" 

10'  o" 

235 

8 

1776 

IOO 

23'  6" 

18'  o" 

423 

16 

3552 

2OO 

23'  6" 

34'  o" 

799 

24 

5328 

300 

23'  6" 

So'  o" 

ii75 

COST  or  STEAM  CONDENSER 
Allow  i  sq.ft.  for  5  Ibs.  of  steam  or  design  by  Orrok's  formula. 


Shell  type  sq.ft.  surface 

IOO 

2OO 

4.OO 

800 

Cost  

$2^0 

$-?QO 

$72  e 

$1280 

Sheet  iron  type,  7'  o"  high,  20'  o"  long $190 

Expansion  Coils.  Allow  275  sq.ft.  of  surface  per  ton  of  ice-making  capacity 
in  plate  plants.  Allow  300  lin.ft.  of  ij"  pipe  in  can  tanks  per  ton  of  ice 
for  ordinary  coil  and  200  to  250  lin.ft.  when  flooded. 

Brine  Coils.     Allow  250  sq.ft.  of  surface  per  ton  of  ice  in  plate  system. 

Brine  Coolers. 


Tons  of  ice 

2 

e 

IO 

2  ^ 

^O 

IOO 

2OO 

Cost  of  double-pipe  brine  cooler  .  . 

$   64 

$120 

$250 

$500 

$1000 

$1950 

$3900 

Cost  of  triple-pipe  brine  cooler  .  .  . 

2  2O 

310 

375 

750 

1500 

3000 

6OOO 

Cost  of  shell-and-tube  brine  cooler 

150 

200 

360 

650 

1250 

2500 

Ammonia  Separators. 
Ammonia  Receiver.     : 


24"X36"  welded $125 

:"X72"  welded 65 


354 


ELEMENTS  OF  REFRIGERATION 

PIPING  AND  FITTINGS 

[List  price  given.] 


Size. 

PIPE. 

ELLS. 

TEES. 

Std. 

Ex.  Hvy. 

Std. 

Ammonia. 

Std. 

Ammonia. 

Screw. 

'  Flange. 

Screw. 

Flange. 

, 

$0.06 
.08* 
.III 

•  17 
.23 
.271 
.37 
•  76i 
1.09 
1.92 

75% 

$o.07i 
.  ii 
.15 

.22 
•  30 

.364 

.50* 

--•1:03 
1-50 
2.86 

70% 

$0.05 
.06 
.08 
.iol. 
.16 
.20 
.28 
-.75 
1.20 
2.75 

70% 

$0.55 
.65 
•  75 
•  90 
1  .20 
1.50 
1.90 
2.90 
S.io 
ii  .40 

70% 

$    .05 
•  30 
.60 

.10 

•45 
•  70 
3-25 
7  .  50 
20.00 
40.00 

70% 

$0.08 
.09 

.  12 

.15 
.23 

.29 
•  41 

I  .IO~ 

1.75 
4.00 

70% 

$0.80 
•  95 

I.  10 

1.35 

1.75 

2  .  30  .; 
2.90 

4-35 
7.80 
17.  10 

70% 

$1.80 

2.  IO 
2.40 
2.70 

3.00 

4-50 
4.80 
12.60 
31-00 
48.00 

70% 

f  

i  
ij 

if::::..,.. 

2                   .... 

3  .-. 

6  

Discount  .  .  . 

Size. 

FLANGES. 

RETURN  BENDS.                               VALVES. 

Pairs. 

Std. 

Ammonia. 

Std. 

Ammonia. 

Std. 

Amm. 

Screw. 

Flange. 

Screw. 

Flange. 

, 

0.40 
.46 
•  52 
.64 
-78 
i  .00 
1.50 

2.  IO 
3-95 

70% 

$1.00 

i  .20 
i.  60 
i.  80 
2.45 
2-95 
3.6o 
6.00 
ii  .20 
20.00 

70% 

$0/26 
.30 
•  40 
.55 
.80 

2.  2O 
6.50 

70% 

$0.95 
1.30 

2.  25 
2.00 

70% 

2.80 
S-20 

70% 

$1.01 

i.  60 

2.  2O 
2.80 
4-OO 
5-50 

8.75 
12.50 
19.00 
37-50 

60% 

$7-50 
8.50 
9-50 
10.50 
13.00 

70% 

$7.40 
8.40 
9-75 
ii.  IS 
17-95 
19-45 
23.  10 
42.50 
84.00 
159.50 

70% 

i 

j        

SI::::::::: 

3  

$::::;:;::: 

Discount      [ 

COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     355 


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ELEMENTS  OF  REFRIGERATION 


IH 

' 

4 

ffi 

N   IO  t^-  O   PO 

M       O  OO 

o'  pi  4  o  co 

MMMNP.J 

>IPE 
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00   PO  N   IO  PO 

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External 
Square. 
Inches. 

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11 

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H 

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O  O  t-  t-  PO 
O\O  PO  t^  M 
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SMM-M-S 

1 

Wire 
Gauge 
Number. 

ci  M  o  ONOO 

t^HM 

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HI  0  O  O  O 

I, 

•§•8 

N    N    Tf  to 

oo  ovo  NOO 

°  ^^^5 

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Actual 
Internal 
Inches. 

10TJ-M    PIO 
O    ON  N   Tf  PO 
N    N    Tfior- 

M    N    Tt-  PO  IO 

ON  P*  Tf  ON  PO 

N  00  OO  PO 

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roO  drooo 

O  N 
10  10  IOO 

Q 

M 

HI    M    HI    N    PI 

PO  Tj-  TfioO 

Nominal 
Internal 
Inches. 

H^*** 

M    M    M    N    N 

HW 

POPO-<tiOO 

Tj-  IO 

t»  ^to  N  rf 
M  pi  ro  too' 

N  00  O  lO^O 

o  O  to  r^  T}- 

^^'SJJ 

M    M 

$£ 

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100  too  PO 

IOOO   PO  M  00 

M    PI    P| 

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M    M 

O    N 
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PO  Tj- 

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N  PO 

O"N  ^00*2 

00  M  r-  ro  to 

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ro  ON  ro  HI  \o 
O  N   M   N   O\ 

N   PO  Tj-lO  IO 

^.  O.  0    N    4 

t^-0 

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o 

§0  0 
0  O 

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nKi-No 

00  Tl-TfoOO 
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PO  to 

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100 

COSTS  OF  INSTALLATION  AND  OPERATION  TESTS  357 

Piping  for  Ice  Storage  Rooms: 


Capacity  in  tons  of  ice .... 
Cost.  . 


2 

$75 


5 

$100 


IO 

$150 


25 

$200 


50 

$350 


IOO 

$450 


2OO 

$750 


CANS  AND  DISTILLING  APPARATUS 

Allow  twelve  3oo-lb.  cans  per  ton  for  flooded  system,  otherwise  fourteen 
3oo-lb.  cans. 


Capacity  in  tons  of  ice 2  5  10  25  50  100          200 

Cost  of  cans  and  tank  with 

coils,  raw  water $950  $1400  $1950  $3850  $6850  $13,250  $26,100 

Cost  of  cans  and  tank  with 

coils,  distilled  water 550  900  1600  3200  5750  11,400     22,900 

Distilling  apparatus 400  500  600  1000  1650  2,500      4,400 

Reboilers,  6o"X6o" $100 

Skimmers,  2o"X 1 20" 40 

Water  coolers  of  15  and  2  ft.  pipe,  20  ft.  long.     Same  as  double- 
pipe  condensers. 
Sponge  filters,  9"X42" $35 

MISCELLANEOUS  APPARATUS  AND  SUPPLIES 

Agitators.     1 2"  belt  driven $  36 

8"  motor  and  agitator 200 

Can  Fillers:     For  300-lb.  cans $15 

Can-filling  hose 40  cts.  per  ft. 

Can  hoists,  3oo-lb.  cans: 

Electric $5°° 

Air 200 

Hand 75 

Ice  dump,  3Oo-lb.  single 5° 

300-lb.  double 9° 

Ammonia 25  to  30  cts.  per  Ib. 

Carbon  dioxide 5  cts-  Per  lb- 

Sulphur  dioxide $i  per  Ib. 

Calcium  chloride $14  per  ton 

Sodium  chloride $14  per  ton 

Water  from  city , 5  to  20  cts.  per  1000  gal. 


358 


ELEMENTS  OF  REFRIGERATION 


ta 

~PO      PO  10  to  IO-K.     oo      ~Oi 

o 

N 

"b'b'bo'b     o     "b"bo     "0*0 

M          M          M    M    M          M   PO 

VstjU            s 

o 

X 

\HH~M*  M"N     "^^Vio^     o"o 

•^t       i^  t^oo  oo  O\       O        ro 

M              HH 

^ 

^IC* 

&• 

5     H«H«Hc.He.       5    Hc.Hc.Hc.5          5    5 

fc, 

O        O\O\O»i-*O        Os        O 

rt        rt  Tt  10  IOO          r*         O 

;   ;   ;   ;            ^  ^  5^ 

:     :  ^  5o5o    5^ 

& 

•        •        •        •  ^               5      2*IHN  O     O            H-»5 

'.     '.     '.     '.  pV       O  t^  ^  >-<  M        POO 

fej 

.   O   M   w          PO        OO 

:  :  :  :       «^^^^    ««o 

•        •    t^  I>  J~-          00            M 

•         v 

'    O  WfrOWW  M            H«5 

^^^       ^      ^^^^^ 

O 

q 

POO  O*      O       OOMOOO        M        O 

MMMM              P)P) 

•         •         •         -^                V      V                                                         ^ 

V 

c^ 

:    ;    ;    ;M"    ^'oV^o     %M 

R3 

:     :  ;o    o,~ooo    o    o 

•      •      •      •                              M  M  M          MM 

••00         OOOMM-*        0          M 

v 

55555        555    -**5        -*«5 

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S 

.       -                                                                                     M 

m 

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eu 

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:     :  : 

ri 

:  :  :  :^  ^  ^  ^  v     ^ 

pi 

•15  >  cS 

§0         0 
oo                    ^  ^ 
o  o  o  M  c\      Jfv  5  i  5       "b"b 

0 

•       •       •       •    O            O  H«-He.H»l-W           O    HI 

:  :  :  :       «-,o  0,0  <->    MM 

•  •  •  -.^  ^^tts  l?s 

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5^555       5^^^v        MO 

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H-»H«5   5   ^        HC<   555        55 

rt 

M    M 

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MM                                                 IN 

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fe                      «« 

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to         g 

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MM<U^           M^^MM          U^ 

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MM             0)    10 

COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     359 


T 


FIG.  A. — York  Compressor. 


360 


ELEMENTS  OF  REFRIGERATION 


PARTICULARS  OF  "  DE  LA  VERGNE  "  STANDARD  HORIZONTAL  AMMONIA 
COMPRESSORS 

ONE  COMPRESSOR  WITH  SIMPLE  ENGINE  AND  Two  COMPRESSORS  WITH  COMPOUND 

ENGINE 


Capacity,  tons  of    ice    melted 

per  24  hours  *  

25 

35 

50 

75 

IOO 

125 

150 

200 

Diameter  compressor  cylinder, 

ins  

10* 

"1 

I3i 

I4s 

16 

18 

20 

22 

Diam.  steam  cylinder,  ins.  .  .  . 

IS 

17 

19 

20 

22 

26 

26 

32 

Stroke,  ins  

18 

20 

22 

26 

30 

33 

33 

36 

R.P.M. 

63 

65 

62 

68 

65 

58 

16 

c*7 

Rated  H.P. 

45 

60 

85 

130 

I7O 

215 

ou 
255 

O  / 
34O 

Dimensions  main  bearings,  ins. 
Diameter  crank  pin   ins 

6iXu 
4* 

7Xi2i 

4i 

8X15 

5* 

9Xi5 
Si 

IOXI8 

6 

II  X20 

7 

12  X22 

7i 

I38Xi24 

Diameter  cross-head  pin,  ins.  .  . 

3 

3i 

4 

4i 

4* 

If 

Si 

si 

Steam  pipe,  ins. 

3 

3 

4 

4 

5 

6 

o 

n 

Exhaust  pipe,  ins  

4 

4 

6 

6 

6 

7 

8 

9 

Ammonia  suction,  ins  

2 

2i 

3 

3 

4 

4 

5 

5 

Ammonia  discharge,  ins  

2 

2 

2i 

3 

3 

4 

4 

5 

Diameter  flywheel,  ins  

96 

IOS 

120 

128 

136 

144 

160 

1  60 

Weight,  do,  Ib  

5OOO 

60OO 

7OOO 

9000 

10,500 

14,000 

17,000 

19,000 

Length  over  all. 

13'  10" 

IS'  l" 

i6'3" 

1  8'  <;" 

2  l'  2fr 

22'  7" 

24'  7/f 

27'  V 

Width  over  all. 

8'  6" 

8'o" 

9'  6" 

/    // 
no 

II'  2" 

12'  6" 

12'  6" 

i        /» 

ISI  I 

Height  above  floor  

6'o" 

6'  5" 

7'  i" 

7'  7" 

8'  2" 

9'  3" 

9'  s" 

10'  o" 

Capacity,  tons  of  ice  melted 
per  24  hours  * 

Diameter  compressor  cylinder 
ins 

Diam.  steam  cylinder,  ins 

Stroke,  ins 

R.P.M 

Rated  H.  P 

Dimensions  main  bearings,  ins. . 

Diameter  crank  pin,  ins 

Diameter  cross-head  pin,  ins.  .  . 

Steam  pipe,  ins 

Exhaust  pipe,  ins 

Ammonia  suction,  ins 

Ammonia  discharge,  ins 

Diameter  fly-wheel,  ins 

Weight,  do.  Ib 

Length  over  all 

Width  over  all 

Height  above  floor 


250 

300 

250 

300 

400 

500 

600 

24 

26 

2-18 

2-2O 

2-22 

2-24 

2-26 

34 

36 

24  &  48 

27&S4 

2Q&58 

32&64 

34&6S 

40 

48 

33 

33 

36 

40 

48 

54 

45 

58 

56 

57 

54 

45 

425 

Sio 

440 

525 

700 

875 

1050 

14X28 

16X28 

14X28 

IS  X28 

17  X30 

18X34 

20  X36 

9 

9i 

12 

I2i 

13 

*3i 

IS 

Si 

9 

41 

Si 

Si 

Si 

9 

7 

8 

5 

6 

7 

7 

8 

10 

10 

14 

15 

16 

18 

20 

6 

6 

6 

6 

7 

8 

9 

5 

6 

5 

5 

6 

7 

8 

174 

192 

160 

160 

174 

192 

216 

23,000 

40,000 

19,000 

23,000 

26,000 

40,000 

50,000 

29'  o" 

33'  o" 

34'  5" 

38'  o" 

40*  2" 

43'  4" 

47'    4" 

1  6'  6" 

1  7'  6" 

12'  6" 

12'  6" 

12'  8" 

13'  0" 

13'  n" 

10'  7" 

II'O" 

10'  8" 

II'  0" 

n'  7" 

13'  0" 

12'   II" 

*  The  ice-making  capacity  of  these  machines  is  from  50  to  60%  of  this  rating. 


FIG.  B. — De  La  Vergne  Compressors. 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     361 


BRUNSWICK  REFRIGERATING  AND  ICE  MAKING  MACHINES 

COMPRESSOR  DATA 

COMPRESSORS  WITH  STEAM  ENGINE 
DIRECT  CONNECTED 

*  is 

•spunoj  'a^ajd 
-UIOQ  ap^s  H3IH 
PUB  JossaiduioQ 
pa^oauuoQ  ^oaaiQ 

tot^OOOiooto 

NOTE.  Complete  J-ton  compression  side  with  automatic  expansion  valve  mounted  on  pedestal,  ready  for  connection  to  coils,  overall 
dimensions:  32  ins.  long,  22  ins.  wide,  38  ins.  high. 

OO        fOPOPOO^^ttOW 
M"         <N          PO         rf        l>        00          M 

•spunoj 
puB  JossaiduioQ 

OlOOOOOOO 

o\Nt^toortooo 

w          N          PO         10         10         l^ 

ait 

•^aa^  puB 
saqouj  '^i{3iajj 

7  11  1  11  11 

•^aa^  puB 
saupuj  't[^piAY 

\o      *o      10      o      ^t*      o      N 

T  ?  ?  ?  ?  r  r  r 

•^aa^  puB 
saqouj  'i^3uaq 

POOOO      o      Tj-TfrM      to 

ii 

0*9 

•saqouj  '^snBqxg 

H       W       "rTN^ro 

•saqoui  'a^oa^s 

w 

•saipuj  'aap 
-UT|XQ  jo  aa^auiBiQ 

He,       He, 

M 

1 
3 

1 
O 

55 

U 

Q 

M 

pq 

03   GO 

*£ 

•spuno^  'a^d 
-0103  apig  H3IH 
puB  jossajduioQ 

oiooootooto 

IOO>00          t^t^rfN          t^ 
M         M        PO       O        l>        O\ 

•spuno<j 
'X|uo  JOSsajduioQ 

tototoooooo 

NOOOO        O\O        PO^O 
NTtOtOMMlOvO 
M         M         N         rf       Tj-       to 

B 

ill 
«JJ 

•^aaj  puB 

???TT?7°? 

•^aa^  puB 

T?T??TltT 

•^aa^ij  puB 
saqouj  'q^Suaq 

NIOOOMMOPOO 

<M      PO     n     •*      |       ^     ^    ^ 

i 

•saqouj  'aSiB^osiQ 

M            Ht            M            W 

•sauoui  -uo^ns 

H^       He,       »W         M        H-       He,       He,       He, 

•OTS  jo  SSSna 

•t!-**1**'*'*'* 

1 

s 

•spunoj  '^t{3Ta^ 

IOIOO          lOlOtOO          O 

«OPOM      r^iOTfN      o 

•saqouj  'aoB^ 

He. 

N        POIOIOOOO        w         w 

•saqoui 
•aa^auiBiQ 

^2    5    S    §    S    5-    5-    X 

•a^mnp^ 
jsd  suot^njoAa-jj 

OlOOOOOOO 
O        t^MOOO        ^fO        •* 

Ili^illi 

•saipuj  'a^oj^g 

CS        fO        •*      O       00       \O       00 

.J3pun*op£S,a 

«  tr  3  -5  o  •?:  o  t: 

*sjapUTtA°Q  jo  jaqurnjsj 

MtHMMHMNN 

•SJnOJJ   ^2   'X^TOBdBQ 

3ux^BJa3uja^  suoj. 

HW      He,                                                   0        to 
'       1        I 

M 

•J9qutn^j 

H*H«W         M         ^frOOO         M 

nunii 

362  ELEMENTS  OF  REFRIGERATION 

DATA  FROM  HIGH-SPEED  ENGINE — ERIE  CITY  IRON  WORKS 


Size  of 
Engine. 

A 

B 

C 

Weight 
of  Fly- 
wheel. 

D 

E 

F 

G 

* 

/ 

Ins. 

Ins. 

Ins. 

Ins. 

Ins. 

Ins. 

Ins. 

Ins. 

Ins. 

10  Xio 

4 

48 

9* 

1345 

IS* 

18* 

36 

28 

75 

103 

ii  Xio 

4 

48 

9* 

1345 

IS* 

18* 

42 

30 

75 

105 

12X12 
13X12 

ill 

54 

2025 

I8J 

22i 

48 

30 

90 

120 

14X14 
15X14 

5* 

60 

14* 

2920 

*xi 

26i 

54 

36 

105 

131 

16X16 
17X16 

I  ? 

72 

16* 

4500 

24i 

29i 

60 

40 

120 

1  60 

18X18 
19X18 

!8 

72 

18* 

5200 

.27! 

39* 

66 

.    48 

131 

179 

Initial 

Size  of 
Engine. 

j 

K 

L 

M 

AT 

Speed. 

Steam 
Pressure. 

I.H.P. 

Ins. 

Ins. 

Ins. 

Ins. 

Ins. 

10X10 

85 

25* 

54* 

99 

Si 

300  to  350 

47  to  104 

ii  Xio 

91 

25* 

60* 

99 

Si 

300  to  350 

j 

57  to  126 

12X12 

13  Xl2 

108* 

30f 

117 

61* 

275  to  325 
275  to  325 

,0 
0 

75  to  162 
87  to  189 

14X14 
15X14 

I30J 

35f 

8o| 

!  135 

7i* 

250  to  300 
250  to  300 

o 

107  to  240 
123  to  275 

16X16 
17X16 

134* 

40  1 

89  i 

ISO 

8xf 

225  to  275 
225  to  275 

0 

oo 

146  to  333 
165  to  370 

18X18 
19X18 

148 

47i 

105* 

167 

92* 

200  tO  225 
200  to  225 

185  to  390 
205  to  435 

FIG.  C.— Erie  City  Iron  Co.  Engines. 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     363 
DATA  FOR  TURBO  GENERATORS 


Power. 

R.P.M. 

Width. 

Length. 

Limit 
Length. 

Height. 

Steam 
Pipe. 

Exhaust 
Pipe. 

K.W. 
35 

100 
200 
2OO 

D.C.  3600 
A.C.  3600 
D.C.  3600 
A.C.  3600 

Ft.  Ins. 

2       IO 

4     10 
4     4& 
5     o 

Ft.  Ins. 
6     6 

12      4f 
12       4£ 

ii      9l 

Ft.   Ins. 
7      ii 
12    Ilf 
12       4i 

13  iof 

Ft.  Ins. 
3       of 
4       9 
4     II* 
4       9 

Ins. 

2 

r. 

si 

Ins. 

1* 

8 
8 

Non- 
condensing 

DATA  FOR  RETURN  TUBULAR  BOILERS 


Shell. 

Tubes. 

A 

Boiler 

B+K 

C 

C' 

D 

E 

'    '    Diam. 

Length, 

Diam. 

No. 

Ins. 

Ft. 

Ins. 

Ins. 

Ft.    Ins 

Ft.  Ins. 

Ft.  Ins. 

Ft.    Ins. 

Ft.  Ins. 

46.5 

42 

IS 

3 

34 

4 

2 

16       2 

2          2 

i      ii 

8        5 

7        9 

65-4 

48 

IS 

3 

SO 

48 

16       2 

2          2 

i      ii 

8      ii 

8        i 

80.  i 

54 

15 

3 

62 

5 

4 

16       2 

2           2 

2           2 

9        6 

8        9 

98.7 

60 

16 

3 

72 

60 

17          2 

2          3 

2           I 

IO          0 

9        i 

131  -9 

66 

18 

3f 

74 

6 

6 

19       6 

2           3 

2           3 

10       8 

9        8 

167.5 

72 

18 

3* 

96 

72 

19       6 

2          3 

2          3 

II           2 

IO          O 

197.1 

78 

18 

3* 

114 

7 

8 

19        8 

2          6 

2          6 

12           7 

IO       IO 

242.0 

84 

18 

3  } 

142 

84 

19        8 

2          6 

2           6 

12        IO 

II         3 

283.0 

90 

18 

168 

9 

0 

19     10 

2           6 

2           6 

13        4 

ii        8 

319.7 

96 

18 

3! 

190 

96 

19     10 

2           6 

2           6 

13        IO 

12          I 

354-6 

96 

20 

3  \ 

190 

9 

6 

21        IO 

2          6 

2          6 

13      10 

12           I 

391-6 

96 

20 

3 

248 

96 

21        IO 

2          6 

2          6 

13     10 

12           I 

jj 

J 

c  to  c 

Boiler 
H.P. 

f 

Cfor  i 
Boiler. 

H 

/ 

K 

L 

M 

v        Shells 
in  Bat- 

Red 
Brick. 

Fire 
Brick. 

tery. 

Ft.  Ins. 

Ft.  Ins 

Ins. 

Ins. 

Ins. 

Ins. 

Ins. 

Ins. 

Ins. 

Ft.  Ins 

46.5 

19     2 

8     o 

33: 

40! 

2 

43 

37 

3 

48 

5-8 

15,000 

1300 

65.4 

19     2 

8     6 

33 

481 

6 

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43 

4 

54 

6-2 

16,000 

1525 

80.  i 

19      2 

O       0 

33: 

48! 

6 

55 

49 

4 

60 

6-8 

16,700 

1650 

98.7 

2O      2 

9     6 

33 

48  i 

6 

61 

55 

4 

66 

7-2 

18,200 

1900 

131.9 

22       2 

IO       O 

33 

6' 

67 

61 

5 

72 

7-8 

22,000 

2100 

167.5 

22       2 

10     6 

33 

Si 

6; 

73 

67 

6 

78 

8-2 

23,OOO 

25OO 

197.1 

22       2 

II       O 

33 

54l 

7 

79 

73 

6 

84 

8-8 

24,OOO 

2625 

242.0 

22       2 

ii     6 

33 

541 

.7 

85 

79 

7 

90 

9-2 

26,000 

2850 

283.0 

22       2 

12       0 

33 

561 

7: 

91 

85 

7 

96 

9-8 

28,OOO 

3050 

319.7 

22       2 

12      6 

33 

561 

7 

97 

91 

8 

IO2 

IO-2 

30,000 

3400 

354-6 

24    2  :  12    6 

33 

561 

7 

97 

91 

8 

102 

10-2 

32.OOO 

3400 

391-6 

24       2         12       6 

561 

7: 

97 

91 

8 

IO2 

IO-2 

32,000          3400 

Other  size  boilers  are  made  between  the  sizes  given  by  varying  length  from  14  to  22  ft. 
and  by  changing  size  and  number  of  rows.  The  thickness  of  shell  is  given  by  the  formula 
pd  =  2tSx  eff. 


364 


ELEMENTS  OF  REFRIGERATION 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS    365 
WATER  TUBE  BOILER  DIMENSIONS 


Boiler  H.P  

75 

ICO 

200 

300 

400 

500 

Columns  and 
Rows     of     4" 
flues  

S~9 

6-9 

10—  o 

1  6—  o 

1  6—  12 

21—12 

A   and  number 
of  drums  

36"  I 

36"  i 

36"  2 

42"     2 

42"  2 

42"  3 

B. 

19'  o" 

1  8'    4!" 

20'   4" 

20'       4" 

20'   4" 

20'  4" 

c  

8'  2" 

8'    2" 

8'  2" 

8'     2" 

8'  2" 

8'  2" 

D  

3'  2" 

3'    2" 

3'  2" 

3'     2" 

3'  2" 

3'  2" 

E. 

4?" 

4!" 

F  

30" 

39f" 

3Qa" 

39f 

39f" 

391" 

/       // 

/      // 

G  

H.  .  . 

7      5 
14'    8" 

7      5" 
14'     8" 

7    2 
14'  8" 

7'     2" 

is'    2" 

9'     2" 
17'     6" 

9      2 
17'     6" 

I  

13'     o" 

13'    o" 

13'  o" 

6'     o" 

6'    o" 

6'  o" 

6'     o" 

6'     o" 

6'     o" 

K  

2'  3^" 

2/  3^" 

2/  3^" 

2'  3i" 

2/  3!" 

L 

is" 

is" 

is" 

is" 

is" 

3 

M 

6'  4" 

6'     4" 

6'     4" 

6'     4" 

8'     2" 

8'     2" 

N  

17'  9?" 

17      92 

19'     9" 

19'     9" 

19'    9" 

19'     9" 

O  
P  

10'     9" 
16" 

16" 

17'     2" 
16" 

24'     2" 
16" 

24'     2" 
16" 

30'     o" 
16" 

Q  

R. 

6'     o" 
24" 

6'    o" 

24" 

7'    o" 
24" 

7'    o" 
24" 

7'     o" 
24" 

7'    o" 
24" 

S  

8" 

8" 

8" 

8" 

8" 

8" 

T 

17" 

17" 

i7"&  24" 

I7"&  24" 

i7"&  24" 

17"  &  24" 

U  .  . 

~'         ~" 

3'  i°" 

W  

9" 

9" 

12" 

12" 

IS" 

15" 

X 

is'    s" 

is'   s" 

IS'     8" 

16'     2" 

17'  n" 

18'    9" 

366 


ELEMENTS  OF  REFRIGERATION 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     367 

ANTHRACITE  SUCTION  PRODUCERS.    DIMENSIONS 


H.P. 

B 

C 

D 

£ 

F 

G 

H 

K 

Width. 

Height. 

IOO 

5'8" 

n'8" 

3'  9" 

3'  3" 

14'  o" 

6'  6" 

7'  2" 

5'  4" 

13'  o" 

20  o 

200 

7    2" 

12'  8" 

4/6// 

4'  8" 

1  8'  o" 

?'  o' 

9   o" 

6'  3" 

15   o 

2l'o" 

300 
400 

8'  8" 
9'  8" 

15'  3" 

16'  o" 

3/5// 

a's* 

5'  8" 
6'  6" 

20'  o" 
20'  o" 

8'  9" 

Q'  3" 

10'  7" 
n'8" 

6'  8" 
7'i" 

17'  6" 

18'  6" 

26'  6" 
26'  6" 

FIG.  F  —  Gas  Producer. 


368 


ELEMENTS  OF  REFRIGERATION 

DIRECT-CONNECTED  GENERATOR 
DIMENSIONS  (Inches) 


K.W. 

Speed. 

Poles. 

B 

C 

D 

A 

E 

F 

G 

H 

/ 

25 

280 

6 

42* 

34* 

15* 

4  or  4! 

i8l 

39 

19* 

18* 

i6f 

50 

260 

6 

48i 

37r& 

is* 

4^  or  6| 

21 

44i 

«A 

195 

19 

75 

250 

6 

54* 

43  H 

19 

5?  or  7* 

22i 

5i 

24H 

2lf 

21 

100 

235 

6 

6o| 

46£ 

19 

6  or  8| 

22* 

56 

27* 

24 

23* 

15° 

2OO 

8 

68| 

S3f 

22 

7  or  10 

24 

64! 

31* 

25 

27! 

200 

1  80 

8 

74* 

59* 

25 

8  or  ii 

26 

7i 

34* 

29* 

29 

300 

150 

10 

88£ 

66| 

25 

10  or  13 

27 

85^ 

41* 

31* 

3i* 

400 

150 

10 

101 

76 

28 

15  or  17 

30 

1015 

48 

34* 

35 

FIG.  G. — Generator. 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS    369 

MOTOR  DIMENSIONS  (Inches) 


H.P. 

Speed. 

Poles. 

A 

5 

c 

D 

£ 

F 

G 

20 

800 

4 

S*& 

54i 

26% 

3if 

15 

*$& 

28 

SO 

650 

6 

62| 

45 

36 

43 

21 

26i 

28! 

80 

600 

6 

7$! 

52 

42f 

49  H 

24 

31 

36f 

IOO 

575 

6 

QO£ 

5«l 

46! 

5*A 

24 

35i 

36f 

125 

550 

6 

93f 

62 

5oi 

57f 

27 

36f 

37! 

FIG.  H. — Motor. 


370 


ELEMENTS  OF  REFRIGERATION 


Power  and  Performance  of  Plants.  Auxiliary  Power.  The 
power  used  by  auxiliaries  in  a  plant  may  be  estimated  from  the 
following  tables  from  which  proportions  may  be  found. 

The  power  used  in  a  loo-ton  compression  plate  plant 
is  given  in  the  Transactions  of  the  American  Society  of  Refrig- 
erating Engineers. 


By 
H.Torrance,  Jr. 

By 
T.  Shipley. 

i  H.P.  Compressor  
Water  pump  —  belt  driven 
Agitator  
Thaw  pump 

300.00 

22O 

} 

30 

1  1  .  6  net 
4-3 
0-3 
0.98 

—  20.46  actual  .  . 
6.60 

O    "C^ 

Boiler  pump. 

I    71 

Air  vacuum  pump  

3-30 
10.00  

Electric  lights  

Electric  crane 

4  80 

Electric  motor  on  cutting 

table  .  . 

...3-63  

51.03 

Auxiliary  power  in  per  cent  of  main  power 17%  J5% 

Steam  per  horse-power  hour 18  Ibs. 

Actual  evaporation  in  boiler  per  Ib.  of  coal 8.8  Ibs. 

8.5X2000X100 

Performance:  —       tons  ice  per  ton  coal  11.2  10  to  15 

351X18X24 

The   following   data  are  taken  from  an  electrically  driven 
raw- water  plant  of  200  tons  capacity: 

Compressor  motor 600  H.P. 

i2oo-gallon  cooling- tower  pump  motor  .  50 

i6oo-gallon  brine-pump  motors 100 

i2oo-cu.ft.  air-compressor  motor 30 

Core-pump  motor 5 

Eight  agitator  motors 24 

209  H.P. 

Auxiliary  power  in  per  cent  of  main  power  35%. 

Air  used.  \  to  1.8  cu.ft.  free  air  per  minute  per  3oo-lb.  can. 

From  a  plant  reported  by  W.-  H.    Doreman,    in   Ice   and 
Refrigera:io;i  for  April,  1915,  the  following  data  are  given: 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     371 

Total  horse-power  per  ton 3.7 

Main  motors 81 .  o% 

Water  pumps 7.2 

Brine  pumps 3.7 

Air  pump 1.8 

Pressure  air  pump 2.7 

Cranes 0.4 

Agitators 4.2 

100.00 

To  operate  a  150- ton  ice  plant  electrically  would  cost  about 
the  same  as  to  operate  by  compound  steam  engine  with  power 
at  i  cent  per  K.W.,  the  saving  in  labor  being  made  up  by  the 
increase  in  the  power  cost.  The  investment  would  be  $20,000 
less  and  20%  of  this  would  represent  an  item  of  $4000  in  favor 
of  the  electric  drive  at  this  unit  cost  of  i  cent. 

Steam  for  Auxiliaries.  The  steam  used  per  twenty-four 
hours  in  a  loo-ton  plate  plant  has  been  given  by  I.  Warner 
in  the  Transactions  of  the  A.  S.  R.  E. 


Compressor  engine 125,703  Ibs.  69 .6% 

Auxiliary  engine  and  pump 45,347  25.2 

Dynamo  engine  (12^  hrs.) S^S2  2-8 

Harvesting  26  cakes 3,088  1.7 

Melting  off  plates 1,290  0.7 


1 80,580  Ibs.  100.0% 

8.5X100X2000 

Performance:    —  — =0.4  tons  of  ice  per  ton  of  coal. 

180,580 

Power  and  Performance  of  Absorption  Plant.  The  power 
used  in  an  absorption  plant  with  plate  ice  is  58.33  I.H.P.  per 
100  tons  capacity.  The  steam  used  is  27  Ibs.  per  I.H.P.  hour. 
The  generator  requires  50  Ibs.  of  steam  per  hour  per  ton  of 
capacity  under  usual  conditions  according  to  H.  Torrance,  Jr. 
The  total  steam  needed  by  pumps  is  58.33X27  =  1575  Ibs.  per 
hour.  The  total  amount  needed  by  generator  is  5000  Ibs.  per 
hour.  The  exhaust  from  the  pumps  could  be  used  in  the  gen- 


372  ELEMENTS  OF  REFRIGERATION 

erator.  The  radiation  from  the  pumps  may  amount  to  one- 
third  of  the  steam  supplied  or  525  Ibs.  of  steam.  This  is  lost. 
The  remaining  1050  Ibs.  may  be  used,  requiring  5525  Ibs.  per 
hour.  The  performance  is 

8.5X2000X100  , .  r 

—  =  12.8  tons  of  ice  per  ton  of  coal. 
5525X24 

Torrance  suggests  operating  an  absorption  plant  with  the 
exhaust  from  a  compression  plant.  Using  figures  above  and 
assuming  25%  of  the  steam  from  the  compression  plant  con- 
densed by  radiation,  the  steam  returned  would  be 

351 X  18X0.75  =4740  Ibs. 
The  amount  condensed  would  be 

4740  X— 5-  =  1580  Ibs. 
"   o-75 

The  amount  consumed  would  be 

4740+1580+1575  =  7895. 
The  performance  of  the  two  machines  together  would  be 

8.15X2000X200      0  ,          ,  .  ft 

— - —  -  =  1 8  tons  of  ice  per  ton  of  coal. 

7895X24 

Performance  of  Producer-driven  Plant.  A  test  of  a  pro- 
ducer plant  for  144  hours  reported  in  the  transactions  of  the 
A.  S.  R.  E.  by  E.  W.  Gallen  Kamp,  Jr.,  showed  that  22.10 
tons  of  ice  were  produced  per  ton  of  coal  excluding  auxiliaries 
or  17.8  tons  with  auxiliaries.  A  performance  of  25  tons  has 
been  reported. 

Labor  Costs.  The  tables  on  pp.  373  and  374,  arranged  from 
averages  of  estimates  given  by  a  number  of  manufacturers,  may 
be  used  to  estimate  the  probable  number  of  men  and  cost  of 
labor: 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     373 


§ 

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Total  
Labor  cost  per  to 

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FRIGERATION 

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Total  
Labor  cost  per  ton.  . 

NOTE.—  In  th 
omit  oilers  and  firem 

374 


ELEMENTS  OF  REFRIGERATION 

COST  OF  FUEL  AND  SUPPLIES  PER  DAY 


TONS  OF  ICE  PER  24 

HOURS 

S 

10 

IS 

20 

25 

35 

So 

75 

IOO 

200 

Fuel  cost  at  $3  per  ton. 

3.25 
3.20 
8.80 
•  So 

6.50 
4.20 
16.80 

•  75 

9-50 
4.80 
19.  20 
1  .00 

12.00 
4-40 
17.00 
I  .  IO 

13.00 
5-00 

20.00 

I.  IS 

16.00  24.00 
7.00  10.00 
28.00  40.00 
i-4S!    i.QO 

34-00 
14.00 
56.00 
2.75 

43-00 

20.00 

80.00 
3-75 

78.00 
40.00 
1  60.0 
7-25 

Oil  at  4  cts.  per  gal  
Electricity  at  2  cts.  per  K.W. 
Oil,  waste,  etc  

Cooling  Water.  Starr  in  Ice  and  Refrigeration  for 
Sept.,  1911,  points  out  that  the  head  pressure  increases  when 
the  quantity  of  water  is  decreased.  This  increases  the  cost 
of  compression  but  decreases  the  cost  of  water  and  the  cost  of 
pumping  water.  There  may  be  some  point  at  which  the  com- 
bined cost  of  compression,  water  and  pumping  water  is  a  mini- 
mum. This  point  will  vary  with  cost  of  water,  lift  of  water 
and  cost  of  compression.  This  should  be  investigated  for  any 
given  problem. 

Cost  of  Water.  B.  C.  Sloat  in  Ice  and  Refrigeration  for 
Dec.,  1910,  gives  the  following  costs  of  pumping  water  per 
1000  gallons: 

Head  lifted,  feet 50  100  150  300 

Deep-well  pump 1.7  cts.  3.4  5.1  10.3 

Air-lift  pump 1.2  3.6  7.7 

Displacement  pump o .  85  ct.  2.3  4.2 

Cities  charge  from  5  to  20  cts.  per  1000  gallons  for  water. 

Cost  of  Supplies  in  Ice  Plant.  Ice  Plant  of  Moderate  Size 
by  Charles  Dickerman  in  Transactions  A.  S.  R.  Ev  1908. 


Year. 

Total 
Tons. 

Tons  per 
Day. 
300  Days. 

Cost  Coal. 

Wages. 

Supplies. 

Repairs. 

Improve- 
ments. 

« 
General 
Expenses. 

1904 
1905 
1906 
1907 

Avera 

6667 
8720 
9M4 
8866 

ge  per 

23 

29 
30 
30 

ton  

$1321.08 
1550.  16 
1481.  15 
1377-05 

$4749.90 
4677.70 
5398.55 
5204.19 

$1266.72 
936.64 
837-25 
887.51 

1354.40 
823.14 
1075.36 
933.8o 

$1352.02 
756.46 
301.15 
556.00 

$  679-23 
1614.48 
604.  26 

$0.172 

$0.600 

$0.118 

$o.  125 

$0.089 

$0.087 

Total  cost  per  ton  exclusive  of  overhead  charges $1.19 

Receipts  per  ton  at  plant $i .  50  to  $8 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     375 

Data  from  plant: 

Capacity,  30  tons. 

Compressors,  two  13X30  vertical. 

Condensers,  double  pipe,  2  and  3-in.  six  banks,  12  high,  18  ft.  tubes. 

Brine  tank,  24  coils  2-in.  pipe,  6  high,  44  ft.  long,  6336  ft. 

Ice  cans,  483  cans,  300  Ibs. 

Two  bulkheads  and  two  engine-driven  agitators  in  tank. 

Fore  cooler  i2-in.  diam.Xi6  ft.  long. 

Ice  house,  60  tons  capacity,  cooled  by  brine. 

Boiler,  66-in.  return  tubular,  18  ft.  long.     Fortyeight  4^-ia.  long. 

Stack,  30-in.,  125  ft.  high. 

Bituminous  coal,  $2.40  to  $2.50  per  ton. 

Water,  3  cts.  per  ton  of  ice. 

Ammonia,  $150  to  $200  per  year. 

Performance,  6|  tons  of  ice  per  ton  coal. 

Cost  of  labor,  fuel  and  supplies  at  a  plant  in  Asbury  Park  was  85  cts.  per  ton} 
3ne-half  of  which  was  labor  cost. 

Load  Factors.  The  load  factor  sometimes  assumed  covers 
one-third  year  at  full  capacity,  one-third  year  at  half  capacity 
and  one-third  at  quarter  capacity.  This  gives 


Load  factor      o  .  583  =  58% 

Nordmeyer  suggests  that  the  operation  at  full  capacity 
for  July  with  no  storage  capacity  represents  15%  of  year's 
demand  (use  of  ice  in  July  equals  15%  of  total  yearly  amount) 


i 


Load  factor  =  - — =0.56  =  56%. 


12 

With  storage  space  the  plant  may  be  run  at  full  capacity 
for  even  the  whole  year.  Of  course  the  cost  of  storage  is 
offset  partially  or  completely  by  the  smaller  fixed  charges  on 
the  smaller  equipment. 

Cost  of  Storage.  W.  E.  Parsons  states  that  it  cost  25  cents 
per  ton  to  store  ice,  hold  it  from  spring  until  midsummer  and 
remove  it  to  delivery  platform  in  a  75-ton  plant.  J.  N.  Briggs 
increases  this  to  45  cents  per  ton  to  cover  the  charge  for  the 
storehouse. 


376 


ELEMENTS  OF  REFRIGERATION 


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COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     377 


COSTS  or  IOO-TON  ICE  PLANT 

By  W.  T.  Price,  in  Ice  and  Refrigeration  for  Dec., 
INVESTMENT 


Steam 
Plant. 

Oil 
Engine 
Direct. 

Oil 
Engine 
Belted. 

Producer 
Gas. 

Engine  and  compressor  
Freezing  system  

$27,000 
27,000 
1,500 

$  34,000 
27,000 
1,500 

$  38,000 
27,000 
1,500 

$   39,000 
27,000 
1,500 

37  ooo 

29,000 

31,000 

35,000 

9,500 

8,700 

9,100 

10,000 

$102,000 

$100,200 

$106,600 

$112,500 

OPERATING  COSTS 


Coal  $3.51  per  ton  with  8  :  i  boiler-evapo- 

$9,45O 

Fuel  oil  3|  cts.  per  gal.     i  ton  to  4  gal.  .  . 
Fuel  oil  35  cts.  per  gal.,  i  ton  to  45  gal.  .  . 
Pea   coal,    anthracite,    $4.50    per   ton,    26 
tons  ice  per  ton  
Supplies:    oil  ammonia,  waste,   6  cts.  per 
ton  with  steam,  7  cts.  per  ton  with  oil 

i  300 

$3,020 
I  500 

$3,400 

I  500 

$3,740 

I  500 

Labor  365  days  

10,600 

10,800 

10,800 

12,250 

Repairs   3% 

3  060 

3  OOO 

3,170 

3,470 

Depreciation  : 
Buildings  3%  

1,110 

870 

930 

1,050 

Equipment  5%.    . 

2,770 

3,120 

3,320 

3,370 

$28,290 

$22,310 

$23,120 

$25,380 

Assuming  33%  full  capacity,  33%  £  capac- 
ity, 33%  i  capacity  gives  21,600  tons  at 

$1.31 

$1.03 

$1.07 

$1.17 

DAILY  LABOR  COST 


Engineer  chief  
Engineer  assistant  

$5.oo 
3.50 

$6.00 
3.50 

$6.00 
3-5O 

$6.OO 
3.5O 

Oilers,  2  shifts  

4.00 
4  5° 

4.00 

4.00 

4-OO 

4  oo 

Tankmen.               .    ...         

8  oo 

12.  OO 

I2.OO 

12  .OO 

4  oo 

4.  oo 

4.  oo 

4.  oo 

Total 

$29  oo 

$29.50 

$29.5O 

$33.50 

378 


ELEMENTS  OF  REFRIGERATION 


COST  OF  ICE  PLANTS  FOR  STEAM  AND  OIL  ENGINE  OPERATION 

L.  K.  Doelling,  A.  S.  R.   E.  Journal,   Sept.,   1915. 
INVESTMENT   COSTS 


Apparatus. 

STEAM  ENGINE  PLANT. 

OIL  ENGINE  PLANT. 

50  tons. 

100  tons. 

200  tons. 

50  tons. 

100  tons. 

200  tons. 

Oil  Engine,  rope  drive  and  foun- 

$14,500 
1,500 

5,500 
14,000 
1,000 
16,000 
S.ooo 

$25,500 
2,500 

10,000 

27,000 
1.500 
35,000 
8,000 

$45,000 
4,500 

18,000 
50,000 
2,500 
60,000 
12,000 

$10,000 
3,ooo 
15,500 

18,000 
50,000 
2,500 
60,000 

12,000 

Piping  for  oil,  water  exhaust  and 
oil  tank 

Boiler  plant  and  foundation.  .  .  . 
Piping  for  steam,   exhaust  and 
water  '  
Steam    engine    and    foundation 
direct  connected. 

$3,ooo 
1,500 
S.ooo 

5,500 
14,000 

1,000 

16,000 
5,000 

$5,5oo 
2,000 
9,500 

10,000 
27,000 
1,500 
35,000 
8,000 

Compressor,  condenser  and  am- 

Freezing  system  

Buildings  
Land  

Total  

$51,000 

$98,500 

$171,000 

$57,500 

$109,500 

$192,000 

OPERATING    COSTS 


Labor,    fuel    and    ammonia   for 

for  216  days  full  capacity.  .  .  . 

$10,314 

$16,740  !  $29,268 

$6,454       $10,908     $18,360 

Labor  for  remainder  of  year.  .  .         2,736 

4,174 

5,832 

2,348 

3,672          5,328 

5%  depreciation  on  equipment. 

1,500 

2,775 

4,950 

1,825 

3,325 

6,000 

3%  depreciation  on  building.  .  . 

480 

1,050 

1,  800 

480 

I,O5O     ;                1,  8OO 

5%  on  total  in  vestment  for  taxes, 
repairs,  water  and  incidentals 

(no  allowance  for  interest  on 

2  55O 

4  925 

8  550 

2,875 

5  475 

9,600 

Total  

$I7,58O 

$29,664 

$5O,4OO     $I3.O82      1    $24.4.30 

$41,088 

Tons  per  year  

IO,8OO 

21,600 

43-OOO 

10,800 

21,600 

43,000 

$1    62 

$i   40 

$1     17 

$i   30 

$i    ii 

$0.96 

(Cost  with  interest)  

(1.86) 

(1.63) 

(1-36) 

(i.57) 

(1.35) 

(I.  13) 

DAILY    OPERATING    EXPENSE 


Labor.                       

$19  oo 

$29.00 

$40.50 

$16.00 

$25.  50 

$37.00 

Fuel  (coal  $3-50,  oil  at  3-5  cts). 
Ammonia   oil   waste 

22.75 

6  oo 

38.50 

IO.OO 

77.00 
18.00 

7.88 
6.00 

15  .00 

IO.OO 

30.00 
18.00 

Total 

$47   75 

$77  50 

$135.  50 

$29.88 

$50.50 

$85.00 

H.  Swan  shows  that  although  a  compound-engine  plant 
would  cost  12%  more  than  the  steam-engine  plant  above  the 
fuel  cost  would  be  so  much  reduced  that  the  cost  of  ice  would 
be  reduced  by  10%. 

L.  C.  Nordmeyer  gives  the  following  costs  for  a  loo-ton 
plant  at  57%  load  factor. 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     379 


COST  OF  PLANT 


Simple  Steam 
Engine. 

Compound  Con- 
densing Steam 
Engine. 

Diesel  Oil 
Engine. 

Buildings 

$60  ooo 

$60  ooo 

$60  ooo 

Machinery. 

6c  ooo 

76  4.00 

87,02'? 

$125,000 

$136,400 

$143,923 

OPERATING  COSTS  PER  TON  PRODUCED 


Cost  of  water  per  ton  .  . 

$0.09 

Cost  of  fuel  per  ton.  .  .  . 

$0.976 

$0.753 

O.226 

At  25  cts.  per  42  gals.  .  . 

(1.03  bbl.  per  ton) 

(0.79  bbl.  per  ton) 

(0.238  bbl.  per  ton) 

Fixed    charges    per    ton 

on  machinery  

0.546 

0.642 

0.821 

Operating  cost  per  ton  . 

0-579 

0.579 

0.516 

Total  cost  per  ton  . 

$2.101 

$1.974 

$1.653 

Fixed    charges   per   ton 

for  building  

0.504 

0.504 

0.504 

Total  

$2.605 

$2  .  478 

$2.157 

Equipment:     Two    6o-ton   refrigera- 
ting machines  and  engines. 
Water  tube  boiler  and  feed  pumps. 

Equipment  :      Two     6c-ton 
compressors      belted     to 
two     225     H.P.      Diesel 

Feed  water  heater,  chimney. 

engines. 

Freezing  system. 

Two  40  K.W.  generators. 

Steam  condensers. 

Raw  water  freezing  system. 

Ammonia  condensers. 

Cooling  tower. 

Air  lift  pumps,  air  compressors. 

Two  circulating  pumps. 

Circulating  water  pump. 

Two  brine  pumps. 

Cooling  tower. 
Brine  pump  and  cooler. 

Cold  storage  piping. 
Piping  and  covering. 

Piping  for  storage. 

Ammonia,  calcium  chloride. 

Piping  for  apparatus  and  covering. 
60  K.W.  generator  and  engine. 

Two-oil  tanks. 
Foundations. 

Ammonia,  calcium  chloride. 

Ammonia  condenser. 

Foundations. 

In  the  above  tables  allowance  has  not  always  been  made 
for  interest  on  the  total  investment.     The  items  should  be  care- 
fully gone  over  and  the  following  percentages  allowed: 
Interest  on  total  cost  (return  on  investment)  ......     5    to    8% 

Taxes  ........................................     i    to    2 

Insurance  (J%  fire  proof,  i%  frame)  .............     \    to    i 

Depreciation  on  machinery  (about  14  years  life  at 

4 

5 
2 


_  _  _ 

Depreciation  on  buildings  (25  years  life  at  5%)  ....  2 

Repairs  to  machinery  ..........................  3    to 

Repairs  to  building  ............................  i    to 


Total i6f  to  24 


380  ELEMENTS  OF  REFRIGERATION 

Ice  Delivery  Data: 

Cost  of  wagons $275 . oo 

Cost  of  horses 300 .  oo 

Cost  of  harness 35 . oo 

Cost  of  feed .50  per  day 

Cost  of  drivers 2.75       " 

Cost  of  helpers 2 .  oo      " 

Mr.  G.  T.  Lawrence  gives  the    following   in   Ice    and   Re- 
frigeration, Apr.,  1913. 

Cost  of  i  team  i  horse  per  month. 

Feed,  shoeing,  driver,  hostler,  repairs $81.12 

Insurance i .  68 

Depreciation,  8^%  on  $720 5 .00 

Interest,  5%  on  $720 3 .  oo 


$90.80 
Cost  of  3-ton  truck  per  month: 

Driver,  repairs,  oil,  gasoline  and  tires $138.00 

Insurance 10 .  oo 

Depreciation,  i6f%  on  $3600  per  month 50.00 

Interest,  5%  on  $3600  per  month 15. oo 


$213.00 

One  truck  can  do  the  work  of  2.93  teams  costing  $266.04 
per  month. 

Amount  retail  delivered  per  day  per  man ......  2  J  tons 

In  Ice  and  Refrigeration  for  Dec.,  1914,  the  following  data 
are  given  for  5-ton  truck: 

Cost  per  day $18 . 45 

Cost  per  mile o. 39 

Cost  per  hour 3 . 80 

Cost  computed  on  equal  time  standing  and  running. 


COSTS  OF  INSTALLATION  AND  OPERATION,  TESTS     381 

REFRIGERATED  RAILROAD  CAR  DATA 

Cost  of  refrigerator  car $1600 

Cost  of  box  car 1 100 

Weight  of  refrigerator  car 46,800  Ibs. 

Capacity 15,000  to  35,000  Ibs. 

Length:   Over  couplers 44'  3!" 

Over  sheathing 40'  1 1 J" 

Inside 39'  lof " 

Inside  between  ice  tanks 33'  2\" 

Width:     Over  sheathing 9'  2§ " 

Inside 8'2f" 

Gauge  track 4'  8j" 

Height:    Rail  to  top  of  brake  shaft 13'  5-}-!" 

Rail  to  running  board 13'    \" 

Rail  to  eaves 12'  $\\" 

Rail  to  coupler 2'  ioj" 

Inside 7'    SA" 

Cubic  capacity:   Total 2444  cu.ft. 

Available 2032  cu.ft. 

Ice  capacity  at  each  end 11,000  Ibs. 

Insulation,  roof:    \"  3-ply  flax  felt 
\"  ship  lap,  2  ply 
f "  ceiling 

Sides:  It"  siding,  f"  furring,  2  ply 
f  "  shiplap 
J",  2  ply,  flax  felt 
«"  lining 

Floor:  |"  flax  felt,  3  ply 
if "  ship  lap  floor 
f"  ship  lap,  3  ply 

Average  amount  of  ice  put  in  at  each  station .   5345  Ibs.  per  car 

Cost  of  icing,  Chicago  to  New  York $16.00 

Cost  of  icing,  California  to  Chicago 62 . 50 

Cost  of  ice  and  salt  per  ton  at  Indianapolis .  .       2 . 85 

Cost  of  cleaning  cars 31  to  80  cents 

Cost  of  stripping  cars $2 . 20 


382  ELEMENTS  OF  REFRIGERATION 

Rates  of  Precooling  by  Mr.  A.  Faget: 

Asparagus  cars  25°  per  hour  air  heated  in  passage  from  16° 

to  38°. 

Celery  cars,  16°  per  hour  air  heated  in  passage  from  14°  to  40° 
Grape  cars,    14°  li  "  "  "      14°  to  31° 

Orange  cars,   8°  "  "  "  "      10°  to  30° 

Air  employed,  8000  cu.ft.  per  car  per  minute. 

Charge  for  precooling $25 .00  per  car 

Charge  for  precooling  and  first  ice .  55 .  oo       ' ' 

Charge  for  icing  to  Chicago 62 . 50 

Charge  for  icing  to  New  York 75 .00 

Cost  of  precooling  and  icing 32 . 50 

Charge  for  use  of  car 7 . 50 


ICE  FOR  PASSENGER  CARS 
20  Ibs.  of  ice  per  car  per  300  miles. 

RINK  DATA 

Use  ij-in.  brine  pipe,  4-in.  centers;  using  about  2  to  3 
lin.ft.  of  pipe  per  square  foot  of  surface.  This  may  be  formed 
in  metal  pan  placed  on  3~in.  cork  boards  and  fed  from  a  brine 
main. 

ICE  CREAM  DATA 
(W.  W.  Wren,  Ice  and  Refrigeration,  May,  1915): 

Cost  per  gallon:  Milk  and  cream 28.4  cts. 

Sugar 3.9 

Ice 5-9 

Salt 2.0 

Fruit i.i 

41-3  cts- 

Over-run  or  swell 68^% 

Shrinkage 6.1% 

42  to  45  Ibs.  of  ice  per  gallon  of  ice  cream. 
Temperature  for  hardening  (6  to  8  hrs.)     o°  F. 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     383 

Temperature  for  ice  making 15° 

Temperature  for  ripening  (12  hrs.)       . .  33° 

Mixing  tank  to  be  refrigerated  with  brine-freezing  machine 

15  minutes  to  batch. 
Power:     i  H.P.  for  5 -gallon  freezer,  single. 

i  H.P.  for  50  gallons  per  hour  in   gangs   from 
i  motor. 

Mr.  J.  H.  Stone  in  the  Transactions  A.  S.  R.  E.  for  1910, 
gives  the  following  data  for  warehouses  using  insulation  of 
various  values  when  the  temperature  of  storage  is  30°  and  the 
average  outside  temperature  for  eight  months  is  70°. 


De-     ! 

De- 

B.t.u. 
per  Sq. 
ft.  per 
24  hrs. 
per 
Degree. 

Cost 
of  In- 
sula- 
tion 
per 
Sq.  ft. 

Cost 
of  In- 
sula- 
ting 

IOOOO 

Sq.  ft. 

Tons 
of  Re- 
friger- 
ation. 

Total 
Tons 

e 

son. 

In- 
crease 
Cost  of 
Insula- 
tion. 

crease 
Cost  of 
Mach- 
chin- 
ery  at 
$450 

Ton. 

Net 
De- 
crease 
in  Total 
Cost. 

In- 
crease 
in 
Fixed 
Charges 
at  15%. 

crease 
in 
Opera- 
tion at 

$1.00 

per 
Ton. 

Net 
De- 
crease 
in  Cost, 
Dol- 
lars. 

4 

1  8  cts. 

$1800 

5-6 

1333 

3 

22 

2200 

4-2 

IOOO 

$400 

$630 

$230 

-$34-50 

$333 

$367.50 

2 

2? 

270O 

2.8 

667 

500 

630 

130 

-   19.50 

333 

352.50 

i.S 

36 

3600 

2.  I 

500 

900 

315 

-   585 

87.75 

167 

79-25 

SO 

5000 

i-4 

332 

1400 

315 

—  1085 

212.75 

168 

-44-75 

Note:  The  last  three  columns  are  changed  from  those 
given  by  Stone.  This  table  gives  decreased  cost  of  any  condi- 
tion on  one  line  over  that  of  the  preceding  line.  If  money 
invested  is  the  important  item  the  2  B.t.u.  condition  is  the  best; 
if  operation,  then  1.5  B.t.u.  is  the  best  condition.  In  this 
analysis  the  value  of  space  taken  by  insulation  is  not  considered. 

STUDY  FOR  MINNEAPOLIS  FOR  COST  OF  NATURAL  ICE  AND  MANUFACTURED  ICE 

FOR  100,000  TONS 

Ice  and  Refrigeration,  March,  1915 

INVESTMENT 

Natural  ice,  storehouse  for  100,000  tons $125,000 

Manufactured  ice — Plant  (275  tons) 400,000 

Storage  60,000  tons 60,000 

Land 20,000 


$480,000 


384 


ELEMENTS  OF  REFRIGERATION 


COST  or  PRODUCTION  PER  TON 


NATURAL  ICE 

Delivery  to  storage $0.30 

Loss o .  04 

Delivery  to  platform o.  15 

6%  interest  on  $1.25  per  ton 0.075 

10%  depreciation  on  $1.25  per  ton  o.  125 

2%  taxes 0.025 

3%  insurance o .  035 

3^%  sinking  fund o. 042 


$o . 792 

Freight o .  400 

10%  shrinkage  in  cars o.  132 

Cars  to  wagon 0.25 


fi.574 
.  2.750 
.  0.432 


Delivery  and  shrinkage 

Overhead  charges  10% 


Selling  price $4-756 


MANUFACTURED  ICE 

Manufacturing  cost $i .  oo 

6%  interest  on  $4.80 o .  288 

i%  insurance  on  $4.80 o .  049 

Repairs o .  192 

2%  taxes 0.096 

3i%  sinking  fund o.  160 


$1.785 

Delivery  and  shrinkage 2  . 642 

Overhead  charges  10% 442 

Selling  price $4 . 869 


DATA  FROM  STUDY  OF  HOUSEHOLD  REFRIGERATORS  IN  ROCHESTER,  N.  Y. 

By  John  R.  Williams 


Weekly  Amounts 

Ice. 

Cost  of  Ice 

per  Year. 

Temperatures. 

50  Ibs  or  less 

7% 
12% 
18% 
47% 
-io% 
6% 

Under  $5..  . 

.    21% 

In  refrigerators: 
Below  45°  
45  to  50°  
50  to  60°     .  . 

•14% 

.27% 
.51% 

si  to  7s;  Ibs.  .  , 

$5  to  $10.  .  .  . 

43% 

76  to  100  Ibs 

$  i  o  to  $  1  5 

j<% 

101  to  200  Ibs  
201  to  300  Ibs  

$15  tO  $20..  . 

$20  and  over 

7% 

...      .     12% 

Over  60°  
Living  Rooms: 
Below  60° 

•   8% 

0% 

100% 

100% 

60  to  70°  
Above  70°  
Cellars: 
Below  <<;0  . 

•42% 
-58% 

•  o% 

Below  60°  

.  8% 

Above  60°. 

02% 

COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     385 


PROPERTIES  OF  SATURATED  AMMONIA,  NH3 

With  Permission  of  G.  A.  Goodenough 


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0.933 

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•  65 

0.606 

90 

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197.3 

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488.5 

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125 

386 


ELEMENTS  OF  EEFRIGERATION 


II 


00  PO    I^OOOOOOO    lONiOf-OO     Tt  rtoO  O  t-  00  'o  l>  -* 

NO     OOwt^PO    O  lO  w  t^  Tt    NOt^iOPO  i-i  O  00  r- 

oypVdg  ooV  t^oo  «o  10  10  4  4co  n  n  ro  N  N  N  N  N  «'  M 

•  N     OvO  O  O  OO     1OO  O\CS^t    PO'-'^'POOs  1OO  O  to 

•IO     t^t^Ot^OO    OOONt^O      N-^twiOOi  If)  l-l  O   & 

'  r-  PO  C\  if)  IH    OO  ro  O»O  PO    M   O\O  ^  N  O  O*  t^O 

•OOiOiOiO    't'tPOPOPO    PONNNN  NWMM 

•  4  <>  4  a  PO  M  ao  N  oo  4  w  oo  4  N  o'  o  PO 
:~;     •    •  t^oo  PO  ^fr-ooo  o    o  OMOO  o\  o  10  M  o 

•  •   If)  If)  If)    VOI/31OIOIO     1OIOOOO 

.     .       .     •  N  PO  ^"    IOO  OO  O*  M     N  rO  ^*O  t^  O\ 

00     lOOt^POM     ^t^WPO'-i 

Tt    lOO  O  t^>OO    OO  O\  O\  O  M 

IO    IOIOIO1OIO     If)  If)  lOO  O 

PO  ^to  i^oo  o    b  N  Tt  100  oo  o\  <-> 

OO  O  O  i-t    1000  N  O  O  O  10  HI 

rtPOOO     w  o  PO  O  O  PO  O  t- 

1OO   t-  t--    00  00    Ov  O 

•OOONN      Tt^-0   POO  NOOW 

MMMMM  MMNN 

^t  ONOO  O  N 
Nt^MPOO     it  ^t  w  Tt  10    PO  POO  POO    O>-iiOTtO\  t^O\t^M 

(MMMMM     r^NOiOO     TtOO  N  O  O     "*  w  t-  POOO     POOO  rj-  O  if)  N  00  rC  O 

III      I      I       III          >-i>-ii-iNNPOPOTfr*3-'OiOOO  t^OO  00  O>  Oi  O  M 

ui  'bg  10  t-  OM-"  PO  <ooo  o  Ttoo    NOOIOO   1010101010  10100100  oooo 


COSTS  OF  INSTALLATION  AND   OPERATION  TESTS    387 


PROPERTIES  OF  SUPERHEATED  AMMONIA—  Continued 

Arranged  from  Goodenough  Tables 

ENTROPY 

•^ 

M 

•guintoA 
oypadg 

{JSJtSdS^-^sSsSSsS"*** 

•"""•&H 

POi-O^l-iOioOOi-i^oO     O*CiOOMp4ro*trtioOt^r~ooO>    OMMN 

•ganiBjgdtugj, 

P)    |   _|_  M  M     PO  Tf  in  t-OO     OM<NPO-3-vOOOOMPO    rto  00   0\  M     ro  Tfro  t- 

^5 

M 

•9tunpA 
oypgdg 

-oo^u,.  aa.jo   o^o.o   -^---^«-   ---- 

•—  SH 

i^S^S  ^S^  S  §  li  §11  o  oo§oo  o^ooo^i"  S°  oE 

-n—  x 

•  0 

•    I     1         M     (N  PO  ^tO  1-    O\'O  M  M  ff)    Tfo  oo  O  M     ro  "*O  r~  O\    M  PO  too 

H 

•guinpA 
oypgdg 

:  :  N  N.  t  °  17H  "  t  °°.  r?°°.  ta  °.  °.  "?HO°.  "?r?000.°.  t«  °.  ^ 

.,U,,UOOH 

-     -  co  Tj-  Tf   i^ioOxOt^oooOOONO     O'-'MrO'^J*    ^fioOt^GO    ooChOM 

.101010  toioioioio  i^ioio  i^o  vooooo  ^Ovoooo  "OOr^c^ 

•g-iniBagduigj, 

;;T'                                         °MMM    MMMMP,    NNNc,N    rorororo 

« 

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.     -PON     MOO\0000     t-  t-OO  lOlO^'t'^POPOPOPONN     NNNM 

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.  wn&H 

I   :  :  :  :  :   :  t^"?  t7°.  ?t°.  t7?r??^  *!  "?'?*"?  ?M.  M.  °. 

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M  OO  O\    1OO  ^fOO     NC^OOOO     ^'MOX.  I—M    OOt^PO 

Tf  Tf  in    uio  O  t-00    OOOvOOM     MNPOrJ-ioOOt-OO 

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MHHINN    NNPOPOPO    *t"*t\n  loO   OOOOOiO    MNTj-ior-    OVMPOUI 

M       MMMMM       -     -;     r,     -, 

388 


ELEMENTS  OF  REFRIGERATION 


PROPERTIES  OF  SATURATED  CARBON  DIOXIDE,  COg 

Based  on  Curves  of  the  Institution  of  Mechanical  Engineers  of  Great  Britain  and  Work 

of  Mollier 


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0.234 

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238 

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0.274 

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260 
283 

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—  IS-  3'n8.  31103.0 

1 

104.0 
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15.9 

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0.260 

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0.348 
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0.248 

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10 

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10 

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102.9 

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0.232 

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20 

422 

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25 

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25 

30 

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11.24 

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0.168 

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75 

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31-5 

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48.6 

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75 

80 

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40.7 

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85 

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45-4 

33.8 

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28.5 

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0.054 

18.52 

85 

87 

1048 

52.0 

22.8 

74-8 

19.7 

3-1 

0.091 

0.040 

0.131 

0.028 

0.044 

22.73 

87 

88.4 

1070 

63.0 

O.O 

63.0 

O.O 

O.O 

0.  112 

0.000 

O.  112 

0.035 

0.035 

28.57 

88.4 

COSTS  OF  INSTALLATION  AND  OPERATION  TESTS      389 


S  1 
g  w 
S  1 

§1 
II 


cfl 


o    3 

en    O 


I! 


BoS 


er  * 
tn 


S  «* 


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OO*O        N  PO  to  M   o*        M  O  O  O  »O  ON  ^toO 

t^t/SPO        N  O   O*OOO        O«OTJ-PON  NM  OO\ 

OOO    OOOOO    OOOOO  OO  OO 

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ff)  if\r>       Ot^O\MN         rtirt  t^OO  O  M  PO  UJ  r~ 

OOO  OOOMM  |_|MMMP<  CSM  NN 

OON         rj-OoO'4-O        00  OOO  00  OOO  "too 

00  ^J-M        00  ^  O  POO        O  t~O  N  N  M  OO  NO 

M  N         N  'tO  r~00         O\  O   M  (N  PO  Tf  10  t>-OO 

Oi  f*5O  fO  ro  ir>  M 

OO    r-O   >O         TfPONNM  MO  O\O\ 

O  d  o  d      d  d  odd  do  o  d 

00    ^tOO   PO         t-~  POO   O>  HI  NO  N  00 

N^tior^      OOOMOI^"  tor--  O\O 

0000     OMMMM  MM  MN 

O  HI  irjoo         O   HI  o   O\OO  t^  O  "<tO 

h  100      OOO\OOM  N1^*  lor* 

•  d  d      d  d  d  d  d  d  d  d  d 

•  00   M          IOOO  00    M    O  "*  N  O  OO 
•00         000*00  OM  MM 

•MOO         ^tOOOOO  O-*  OTt 

•  POi/}       Ot^OOO\O  MM  rj-io 

o  Tfoo  ^f  Oi  too  o  r- 

•  •     •         N  M  O  O  Ov  OOO  00  t- 

...  MMMMQ  OO  OO 

...      odd  d  d  d  d  d  d 

PO  too  OvO  O\  t-  M  \r> 

OO  O\  O  M  N  fO  *s>  t^OO 

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390 


ELEMENTS  OF  REFRIGERATION 


|g 

O  O  O  to  O        iflOoOOOO       00  M  00  O  t^ 
O  O  N  ON  t^       to  ^t  N  M  o        r^O  PO  N  O 

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00  IOIOOO 

0*  t*-         Ov 

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II 

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OOOOO        OOOOO        OOOOO 

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POONOOO         ON  M  ^f  J^-  't       PO  'tO  00  O 
PO  'tO  00  Oi        0   (S  PO  4  10       0  00  0   «'  4 

't  MO  ON  PO 

o  oo'  o  o  N 

t^  PO        O  OO 

POO        00  O 

w 

0 

gw 

O   't  'too  O         OOOOOO't       OOOONrf 

OOil-llOPO           P^NMOv^t           Mt^OOMOO 

(N  O  00  00  O 

dv  o  o  o.  o 

O  -t      ON 

00   ON        IOOO 

00   ON        ON 

HQ 

T  ' 

•     •     -0000         MOO>OPOO       OOOOON 
•     •      •  't  >-i         O  00  t^O  10        't  N  M  OOO 

PO  O    0    N   »0 

O  O        fOO 

PO  N           MO 

•    -oo      ooooo      ooooo 

ooooo 

o  o'      o'  o' 

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U 

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:  :  :  ' 

Saturation 
Temn.  Dee.  F. 

i 
i 

TTTT  '    ' 

0  10  WO  0 
>O  IOOO  t^ 

£00  oo    '• 

Pressure, 
T,hs.  npr  Sn.in. 

1 

§0000      ooooo      ooooo 
<N    -tO  00          O    M    •'tO  OO          O    >O  O   IO  O 

-  0  0  0  0 
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O  t~  t^OO  00 

ooooo 

O  O  t^  O  O 

O.O  Q  M  <N 

COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     391 

PROPERTIES  OF  SULPHUR  DIOXIDE,  SO2 

Based  on  Curves  of  the  Institution  of  Mechanical  Engineers  of  Great  Britain  and  Work 

.  of  Lange 


I 

o    . 

ib 

0         . 

I 

M    • 

c 

JI 

84; 

al 

l& 

V 

^ 

£ 

_J 

15 

%j 

"S  u-»-3 

%  O  i_ 

3| 

£g 

0 

o 

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•8 

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'empera 
Degrees 

ressure, 
Sq.in. 

3t 

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O  rt  ft 

|ll 

H 

P 

>».s 

p 

II 

M> 

11 

83s 

lit 

<£  0£ 

o  ft   * 

empera 
Degrees 

H 

04 

w 

1 

w 

W 

H 

w 

C/3 

tt> 

C/3 

H 

/ 

P 

i' 

r 

i" 

p 

* 

s' 

r/t 

s" 

< 

v" 

m 

t 

-25 

S.i 

—  17-4 

165.5 

148.1 

135.0 

13.1 

—0.038 

0.380 

0.342 

O.OI 

13.89 

0.072 

—  25 

—  20 

5-9 

-15-9 

164.9 

149.0 

135.9 

13.  i 

-0.035 

0-375 

0.340 

O.OI 

12  .02 

0.083 

—  20 

—is 

6.8 

—  14.4 

164.2 

149.8 

136.6 

13.2 

—0.031 

0.369 

0.338 

O.OI 

10.42 

0.096 

—  15 

—  10 

7-9 

-12.9 

163.6 

150.7 

137.4 

13-3 

—0.028 

0.364 

0.336 

O.OI 

9.  12 

O.IIO 

—  IO 

-   5 

9-1 

-ii.  4 

162.8 

151.4 

138.  i 

13-3 

—0.025 

0.358 

0.333 

O.OI 

8.05 

0.124 

-5 

o 

10.4 

—9.9 

162.0 

152.  i 

138.7 

13-4 

—  O.O2I 

0.352 

0.331 

O.OI 

7.12 

0.140 

0 

5 

11.  8 

-8.3 

161.3 

153.0 

139.5 

13-5 

—  O.OI8 

0.347 

0.329 

O.OI 

6.27 

0.159 

5 

10 

13-3 

-6.8 

160.  5 

153.7 

140.1 

13.6 

—  O.OI5 

0.342 

0.327 

O.OI 

5.56 

.180 

10 

15 

15-0 

-5-3 

159-7 

154-4 

140.7 

13-7 

—  O.OII 

0.336 

0.325 

O.OI 

4-95 

.202 

IS 

20 

17.0 

-3-8 

I59.I 

155.3 

141-5 

13.8 

—  0.008 

0.332 

0.324 

O.OI 

4.42 

.225 

20 

25 

19.2 

—  2.2 

158.3 

156.  i 

142.1 

14.0 

—  0.005 

0.326 

0.321 

O.OI 

3.96 

.253 

25 

30 

21.5 

-0.6 

157.4 

156.8 

142.5 

14.  i 

—  O.OOI 

0.321 

0.320 

O.OI 

3.56 

.281 

30 

35 

24.0 

1.0 

156.3 

157.3 

143.1 

14.2 

0.002 

0.316 

0.318 

O.OI 

3-20 

0.312 

35 

40 

26.7 

2.6 

155.4 

158.0 

143.7 

14-3 

0.005 

0.311 

0.316 

O.OI 

.88 

0.347 

40 

45 

29.8 

4.3 

154-3 

158.  6 

144.2 

14.4 

0.008 

0.306 

0.314 

O.OI 

.61 

0.383 

45 

50 

33-0 

6.0 

153.3 

159.3 

144.8 

14-5 

O.OI2 

0.301 

0.313 

O.OI 

.36 

0.424 

50 

55 

36.5 

7-7 

152.1 

159-8 

145.3 

14-5 

O.OI5 

0.296 

0.311 

O.OI 

•  15 

0.465 

55 

60 

40.4 

9-3 

151.1 

160.4 

145-8 

14.6 

0.018 

0.291 

0.309 

O.OI 

.96 

0.510 

60 

65 

44-7 

II  .0 

149.9 

160.9 

146.2 

14-7 

O.02I 

0.286 

0.307 

O.OI 

.78 

0.562 

65 

70 

49-2 

12.7 

148.8 

161  .  5 

146.8 

14.7 

0.025 

0.281 

0.306 

O.OI 

.62 

0.617 

70 

75 

54-0 

14.4 

147.6 

162.0 

147.2 

14.8 

0.028 

0.276 

0.304 

O.OI 

.48 

0.676 

75 

80 

59-3 

16.1 

146.4 

162.5 

147.7 

14.8 

O.O3I 

o.  271 

0.302 

O.OI 

.37 

0.730 

80 

85 

64.9 

17.8 

I45-I 

162.9 

148.0 

14.9 

0.034 

0.266 

0.300 

O.OI 

.25 

0.800 

85 

90 

70.9 

19-5 

143.9 

163.4 

148.5 

14.9 

0.037 

o.  262 

0.299 

O.OI 

.  15 

0.870 

90 

95 

77-5 

21.3 

142.5 

163.8 

148.8 

15.0 

0.041 

0.257 

0.298 

O.OI 

.05 

0.952 

95 

IOO 

84.4 

23.  1 

140.9 

164.0 

149.0 

15.0 

0.044 

0.252 

0.296 

O.OI 

0.96 

1.042 

IOO 

105 

91.8 

24-8 

139-4 

164.2 

149.3 

14-9 

0.047 

0.247 

0.294 

O.OI 

0.88 

1.136 

105 

no 

99-4 

26.6 

137-7 

164.4 

149-5 

14.9 

0.050 

o.  242 

o.  292 

O.OI 

0.82 

I  .  22O 

no 

us 

107.2 

28.4 

136.3 

164.7 

149.8 

14-9 

0.053 

0.237 

0.290 

O.OI 

0.77 

1.299 

us 

392 


ELEMENTS  OF  REFRIGERATION 


i<§  O  -O  O         v§  O  S 


<N   00    10  OO   O 


rl-M 


i      I  MWN          c^roro^l"'^'        lo^oioOO         t^r-*ooO\O\ 


i 


O   OO  10    N 


O    M    *3-\O 
00    Oi  O    w 


..III 


o    P<        O         MIOOONIO 


•uybg  J9d  'sqq  aanssajj 


M      MMMMM      MMMM(N      NNNNf) 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     393 


ENTROPY. 

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M     HI     HI     H              M 

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394  ELEMENTS  OF  REFRIGERATION 

TABLE  or  CHLORIDE  OF  CALCIUM  (CaCl2)  SOLUTION 


Specific 
Gravity 
at  60    F. 

Degrees 
Beaum6 
at  60°  F. 

Degrees 
Salom- 
eter  at 
60°  F. 

Lbs. 
(CaCls) 
per  gal- 
lon So- 
lution. 

Lbs. 
(CaCU) 
per  Cu. 
ft.  Solu- 
tion. 

Percent- 
age 
(CaCU) 
by 

Weight. 

Freezing- 
point  F. 

Specific 
Heat  at 
32    F. 

Weight 
per 
Gallon 
at  60°  F. 

.O2I 

3 

12 

k 

3l 

3 

+  20 

0.965 

8-54 

•  043 

6 

27 

I 

7* 

5 

+  27 

0.920 

8.70 

.066 

9 

36 

a 

g* 

7 

+  25 

0-883 

8.88 

.074 

10 

40 

if 

»i 

9 

+  23 

0.868 

8.96 

.082 

ii 

44 

if 

13 

10 

+  21 

0.857 

9-05 

.099 

13 

52 

2 

-15 

12 

+  18 

0.830 

9.19 

•US 

15 

62 

2l 

17 

14 

+  14 

0.808 

9.29 

.  160 

20 

80 

2^ 

J9 

18 

+4 

0-753 

9-65 

.179 

22 

88 

3 

«I 

20 

-J-5 

0.732 

9-83 

.198 

24 

95 

3^ 

26 

22 

-8 

0.714 

IO.OO 

.219 

26 

104 

4 

3° 

24 

-17 

0.695 

10.  16 

•239 

28 

112 

4i 

34 

26 

-27 

0.678 

10.32 

.261 

30 

I  2O 

5 

37^ 

28 

-39 

0.661 

10.50 

.283 

32 

128 

5^ 

4i| 

30 

-54 

0.643 

10.72 

If  more  chloride  is  used  the  freezing-point  is  raised.     Use  about  i   ton  of 
CaCl2  for  each  ton  of  ice-making  capacity. 


TABLE  OF  SODIUM  CHLORIDE  (SALT)  SOLUTION 


Specific 
Gravity 
at  39°  F. 

Degrees 
Beaume 
at  60°  F. 

Degrees 
of 
Salom- 
eter  at 
60  °F. 

Pounds 
of  Salt 
per  Gal- 
lon of 
Solution. 

Pounds 
of  Salt 

CuGft. 

Percent- 
age of 
Salt  by 
Weight. 

Freezing- 
point 
Fahren- 
heit. 

Specific 
Heat. 

Weight 
per  Gal- 
lon at 
39°  F. 

1  .007 

I 

4 

0.084 

.628 

I 

31-8 

0.992 

8.40 

1.015 

2 

8 

o.  169 

1  .  264 

2 

29-3 

0.984 

8.46 

1.023 

3 

12 

0.256 

1.914 

3 

27.8 

0.976 

8-53 

1.030 

4 

16 

0-344 

2-573 

4 

26.6 

0.968 

8-59 

1.037 

5 

20 

0-433 

3-238 

5 

25-2 

0.960 

8.65 

1-045 

6 

24 

0-523 

3.912 

6 

23-9 

0.946 

8.72 

1.053 

7 

28 

0.617 

4.6l5 

7 

22.5 

0.932 

8.78 

I  .061 

8 

32 

0.708 

5-295 

8 

21.2 

0.919 

8.85 

1.068 

9 

36 

p.  802 

5-998 

9 

19.9 

0.905 

8.91 

1  .076 

10 

40 

0.897 

6.709 

10 

I8.7 

0.892 

8-97 

1  .091 

12 

48 

i  .092 

8.168 

12 

16.0 

0.874 

9.10 

I.H5 

15 

60 

1.389 

10.389 

15 

12.  2 

0-855 

9.  26 

I-I55 

20 

80 

1.928 

14.421 

20 

6.1 

0.829 

9.64 

if; 

i.F96 

24 
25 

96 
100 

2.376 
2.488 

17.772 
18.610 

24 
25 

1.2 

o-5 

0-795 
0.783 

9.90 
9-97 

1.204 

26 

104 

2.610 

19.522 

26 

i  .1 

0.771 

10.04 

COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     395 

Correction  for  temperature  of  aqua  ammonia  to  reduce 
Beaume  readings  to  60°  readings  subtract  J°  Beaume  for  the 
following  number  of  degrees  F: 

From  18  to  20°  B.  for  each  8°  F.  above  60°  F. 
From  20  to  22°  B.  for  each  7°  F.  above  60°  F. 
From  22  to  23^°  B.  for  each  6°  F.  above  60°  F. 
From  23^  to  25^°  B.  for  each  5°  F.  above  6od  F. 
Above  this  for  each  4°  F.  above  60°  F. 


COMPARISON  OF  THERMOMETERS 


Cent. 

Fahr. 

Cent. 

Fahr. 

Cent. 

Fahr. 

-40 

—  40.0 

8 

46.4 

56 

132.8 

-38 

-36.4 

IO 

50.0 

58 

136.4 

-36 

-32.8 

12 

53-6 

60 

140.0 

-34 

-29.2 

14 

57-2 

62 

143-6 

-32 

-25-6 

16 

60.8 

64 

147.2 

-3° 

—  22  .O 

18 

64.4 

66 

150.8 

-28 

—  18.4 

20 

68.0 

68 

154-4 

-26 

-14-8 

22 

71.6 

70 

158.0 

-24 

—  II  .2 

24 

75-2 

72 

i6!.6 

—  22 

-7.6 

26 

78.8 

74 

165.2 

—  2O 

-4.0 

28 

82.4 

76 

168.8 

-18 

-0.4 

3° 

86.0 

78 

172.4 

-16 

+3-2 

32 

89.6 

80 

176.0 

-14 

6.8 

34' 

93-2 

82 

179.6 

—  12 

10.4 

36 

96.8 

84 

183.2 

—  10 

14.0 

38 

100.4 

86 

186.8 

-8 

17.6 

40 

104.0 

88 

190.4 

-6 

21  .  2 

42 

107.6 

90 

194.0 

-4 

24.8 

44 

III  .  2 

92 

197.6 

—  2 

28.4 

46 

II4.8 

94 

2OI  .2 

0 

32.0 

48 

Il8.4 

96 

204.8 

2 

35-6 

5° 

122.0 

98 

208.4 

4 

39-2 

52 

125.6 

100 

212.0 

6 

42.8 

54 

129.  2 

TESTING  REFRIGERATING  APPARATUS 

Tests  of  refrigerating  apparatus  are  difficult  to  perform 
because  the  changes  of  temperature  in  various  parts  of  the  appa- 
ratus are  very  slight,  because  the  weight  and  quality  of  the 
refrigerating  medium  is  difficult  to  determine  and  because  the 


396  ELEMENTS  OF  REFRIGERATION 

errors  at  start  and  finish  of  the  test  make  it  necessary  to  carry 
the  test  over  a  considerable  time. 

Tests  are  necessary  to  determine  the  effects  or  values  of 
new  devices  and  alterations  and  particularly  to  determine  whether 
or  not  the  guaranteed  amount  of  refrigeration  or  the  guaran- 
teed refrigerating  effect  has  been  obtained. 

To  find  the  yield  of  the  apparatus,  the  refrigerating  effect 
may  be  measured  from  the  ammonia  or  from  the  brine  or  in 
an  ice  plant  the  amount  of  ice  produced  may  be  found.  If  the 
guarantee  is  the  production  of  a  certain  amount  of  ice  or  the 
cooling  of  certain  rooms  to  a  definite  temperature  with  a  given 
amount  of  power  and  cooling  water  this  test  is  simple  except  for 
the  length  of  test,  which  should  never  be  less  than  twenty-four 
hours  and  would  be  much  better  if  continued  for  one  or  two 
weeks.  When,  however,  the  refrigerating  effect  is  to  be  found 
the  test  is  difficult  because  of  the  quantities  to  be  measured. 

The  refrigeration  produced  from  the  ammonia  is  given  by 

Qr=M(ii-h)\ 

M  =  weight  of  ammonia  in  given  time; 
2*1=  heat  content  in  suction  main  leaving  expansion  coil; 
4=  heat  content  at  entrance  to  expansion  valve. 

To  determine  this,  the  various  factors  on  the  right-hand 
side  of  the  equation  must  be  found.  The  weight  of  ammonia, 
M ,  may  be  found  by  collecting  the  ammonia  in  a  receiver 
resting  on  a  platform  scale.  This  is  connected  to  the  piping  sys- 
tem by  a  long  piece  of  pipe  so  that  there  will  be  only  a  slight 
effect  from  the  rigidity  of  the  pipes.  If  the  pipes  are  10  ft. 
long  the  weight  necessary  to  deflect  the  pipe  an  amount  equal 
to  the  movement  of  the  scale  platform  will  be  so  small  that 
little  error  results.  By  using  two  receivers,  one  may  be  filling 
while  the  other  is  being  emptied.  The  ammonia  may  be  col- 
lected in  two  tanks  and  the  volumes  measured,  this  being 
changed  to  weight  by  calibration.  Care  must  be  taken  to  have 
no  pockets  in  the  piping  in  which  the  ammonia  may  collect. 
In  fact  the  uncertainty  of  the  amount  of  ammonia  which  may 
lodge  in  pockets  makes  this  method  a  difficult  one  and  for  that 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     397 

reason  in  some  tests,  such  as  those  at  the  Eastman  Kodak  Co., 
the  refrigeration  is  measured  from  the  brine  side. 

The  quantities  i\  and  is  are  difficult  to  determine  if  by  chance 
there  are  liquid  and  vapor  present  together.  To  prevent  this, 
the  liquid  going  to  the  expansion  valve  is  after-cooled  so  that 
it  is  below  the  temperature  of  vaporization  corresponding  to 
the  pressure  and  must  be  all  liquid  (hence  iz=qz)  and  the 
vapor  entering  the  suction  valve  is  slightly  superheated  so  that 
the  quality  may  be  determined  by  a  thermometer 


In  this  way  it  is  possible  to  find  the  value  of  i\  and  i%.  The 
compression  is  dry  compression.  If  it  is  desired  to  have  wet 
compression  it  would  be  possible  to  have  slightly  superheated 
ammonia  in  the  suction  pipe  and  add  an  amount  of  liquid 
ammonia  from  a  calibrated  tank. 

The  thermometers  placed  in  the  thermometer  wells  are 
subject  to  errors,  due  to  the  warming  of  the  stem  if  any  mercury 
projects  above  the  well,  and  if  none  projects  above  there  is 
difficulty  in  reading  the  thermometer,  as  the  stem  often  freezes 
fast  to  the  well  on  the  suction  side.  To  correct  for  stem  error 
it  is  well  to  determine  the  temperature  of  the  stem  ts  by  a  small 
thermometer  tied  to  the  stem  and  if  tt  is  the  reading  of  the 
thermometer,  and  /„  is  the  reading  of  the  point  of  the  ther- 
mometer opposite  the  edge  of  the  well  so  that  the  number 
of  degrees  exposed,  above  the  well  is  tt  —  tw,  the  correction  to  be 
added  to  the  reading  is 

At  =  0.000088  (tt  -  t,)  (tt  -  O  . 

This  assumes  that  the  length  (tt  —  tw)  is  heated  (tt  —  ts) 
degrees  above  the  temperature  it  should  have  been,  and  0.000088 
is  the  difference  between  the  coefficient  of  expansion  of  glass 
and  mercury.  Constant  immersion  thermometers  which  have 
been  calibrated  to  read  correctly  in  rooms  *of  a  certain  tem- 
perature when  immersed  to  a  mark  on  the  stem  may  be  used  with 
no  correction. 


398  ELEMENTS  OF  REFRIGERATION 

To  save  corrections  and  troubles  in  observation,  thermo 
couples  or  resistance  thermometers  may  be  used. 

Calibrated  gauge  readings  as  well  as  temperatures  are  neces- 
sary on  suction  and  discharge  to  determine  the  quantities  i\ 
and  2*3.  The  suction  pressure  is  often  measured  by  using  a 
mercury  U-tube  so  that  small  pressure  differences  may  be  read. 

On  account  of  the  errors  in  the  method  above,  the  refrigera- 
tion is  sometimes  determined  from  the  brine,  which  is  cooled 
by  the  ammonia. 


Mi)  =  weight  of  brine; 
c  —  specific  heat  of  brine; 

to  =  temperature  of  brine  at  outlet  from  cooler; 
/,  =  temperature  of  brine  at  inlet  to  cooler. 

In  this  case  the  weight  of  brine  -Mb  is  measured  by  weighing 
in  large  tanks;  by  the  use  of  a  meter  which  is  calibrated  at 
intervals  during  test;  by  the  use  of  a  Venturi  meter  or  weir. 
The  calibrations  of  these  pieces  of  apparatus  are  absolutely 
necessary. 

The  specific  heat  c  must  be  determined  by  a  formula  from  the 
specific  gravity  of  the  brine  and  the  temperature  or  by  tables 
given  earlier  or,  what  is  better,  by  an  experimental  determination 
made  in  a  Dewar  flask  by  finding  the  watt  hours  used  in  a  coil 
and  required  to  warm  a  certain  amount  of  brine  between  the 
temperatures  used  during  the  test.  Corrections  can  be  made 
for  radiation  by  cooling  curves  and  the  water  equivalent  may  be 
found  by  method  of  mixtures  or  by  heating  distilled  water. 
In  finding  c  by  the  formula  or  table  the  mean  temperature 
is  used  and  the  specific  gravity  is  determined  by  a  hydrometer 
of  some  form. 

The  temperatures  to  and  tt  are  subject  to  the  same  corrections 
mentioned  before  and  because  the  difference  between  them  is  so 
small  the  thermometer  should  be  graduated  to  tenths  of  a  degree, 
or  smaller,  divisions. 

The  use  of  Beckman  thermometers  would  prove  of  value 
here. 


COSTS  OF  INSTALLATION  AND   OPERATION  TESTS     399 

The  power  of  the  engine  required  to  drive  the  compressor 
and  the  power  of  the  compressor  are  determined  by  indicator 
diagrams.  The  small  clearance  on  the  compressor  makes  it 
necessary  to  use  close  and  small  connections  for  the  indica- 
tors as  the  increase  of  clearance  when  the  indicator  is  opened 
will  change  the  form  of  card.  It  would  be  well  to  have  a  com- 
pensating volume  to  cut  out  when  the  indicator  is  connected 
or  the  indicator  might  be  placed  so  that  the  piston  would  move 
vertically  downward  and  the  passage  from  the  cylinder  could  be 
filled  with  oil  so  that  this  volume  is  not  filled  with  ammonia. 
The  usual  formula  for  horse-power  is  used. 

It  is  necessary  to  test  the  springs  and  have  the  reducing 
motion  correct. 

The  amount  of  cooling  water  is  weighed,  metered,  passed 
through  an  orifice  or  over  a  weir  and  its  temperature  is  deter- 
mined by  thermometers.  The  heat  is  given  by 


In  all  cases  the  machines  should  be  brought  to  an  operating 
condition  before  starting  the  test  and  a  running  start  should 
be  made.  With  brine  to  determine  refrigeration  ten  hours 
after  steady  conditions  are  obtained  may  be  sufficient,  although 
with  ammonia  a  longer  test  must  be  used.  In  testing  absorp- 
tion machines  calibrated  meters  are  used  to  determine  the 
flow  of  liquor  and  the  strength  of  the  liquor  is  determined 
by  drawing  off  samples  and  using  a  hydrometer  to  give  the  speci- 
fic gravity.  Thermometers  and  gauges  give  the  conditions  at 
the  various  points.  Meters  are  used  to  measure  the  cooling 
water  and  thermometers  give  the  temperatures  from  which 
the  heat  may  be  determined.  The  drip  from  the  separator 
may  be  determined  by  passing  it  into  one  of  two  cylinders  and 
measuring  its  volume  on  the  way  to  the  analyzer. 

The  test  of  ice  plants  should  extend  over  a  number  of  days 
five  or  seven,  and  in  this  test  the  ice  is  pulled  at  regular  inter- 
vals during  the  twenty-four  hours.  The  test  is  started  after 
the  plant  has  been  run  at  least  seventy-two  hours  to  get  steady 
conditions. 


400  ELEMENTS  OF  REFRIGERATION 

General  observations  should  be  made  at  fifteen-minute 
intervals.  These  include  the  following:  Temperatures:  out- 
side atmosphere,  engine  room,  refrigerated  rooms,  condensing 
water  at  inlet  and  outlet,  brine  at  inlet  to  cooler  and  at  outlet, 
ammonia  at  entrance  to  expansion  valve  and  at  entrance  to 
suction  main,  at  suction  valve  and  at  discharge  main  on  com- 
pressor, at  inlet  and  outlet  to  jacket;  pressures  on  suction  and 
discharge  main,  and  in  expansion  coil,  barometer;  volume 
shown  by  meter  on  brine  line,  condensing  water  line  and  jacket 
water  line,  indicator  cards,  revolutions  of  compressor,  weight 
of  water  going  to  ice  tanks  with  temperature,  weight  of  water 
left  unfrozen,  weight  of  coal,  weight  of  boiler  feed,  feed  tem- 
perature, calorimeter  readings,  flue  gas  temperature. 

The  computation  for  such  a  test  will  be  given  in  the  next 
chapter. 

For  absorption  machines  the  readings  are  somewhat  similar 
and  are  used  in  the  same  manner. 

A  form  of  test  has  been  discussed  by  the  A.  S.  R.  E.  in  its 
proceedings. 

The  following  data  are  obtained  from  a  series  of  tests: 

RESULTS  or  TEST  ON  DOUBLE-ACTING  COMPRESSOR,  MADE  BY 
THE  DE  LA  VERGNE  Co.  AT  THE  EASTMAN  KODAK  Co., 
DATE  FEB.  5,  1908 

Temperature:  Discharge  ammonia  R.H 149.44°  F. 

L.H 143. 36°  F. 

Suction  at  compressor,  before  liquid 

injection 17 . 80°  F. 

At  brine  cooler 19.40°  F. 

Before  expansion  valve 58.91°  F. 

Brine  at  inlet  to  cooler 25 . 11°  F. 

Brine  at  outlet  from  cooler 14.81°  F. 

Engine  room 65 . 85°  F. 

Ammonia  receiver  room 55 . 58°  F. 

Outside  atmosphere 14.93°  F, 

Revolutions  in  i5-minute  compressor 512.1 

Revolutions  in  i5-minute  brine  pump 419 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     401 

Specific  heat  of  brine o. 678 

Weight  of  brine  per  revolution 41-15  Ibs. 

Specific  heat  of  liquid  ammonia. .  . . ' i .  i 

Pounds  of  liquid  ammonia  in  15  min 236.6 

Pressures:    Suction  at  cooler 20.45 

at  compressor 20 . 03 

at  condenser 185 .06 

Steam  at  engine 84 . 1 1 

Barometer 15.01 

M.E.P.  Head  end 38 . 95 

Crank  end 39-67 

I.H.P ..  55.83 

Tons  of  refrigeration  by  brine 36 . 91 

Equivalent  tons  with  20  Ib.  suction 36.88 

I.H.P.  per  ton i .  514 

Size  of  compressor.  ..  njx 22  — (2^  piston   rod)   double  acting 
Size  of  engine 22X22  (3!  piston  rod) 

RESULTS  OF  TEST  ON  SINGLE-ACTING  COMPRESSOR  MADE  BY 
THE  YORK  MFG.  Co.  AT  THE  EASTMAN  KODAK  Co., 
DATE  MAR.  9,  1908. 


Temperatures:   Discharge  ammonia  R.H 248.3°  F. 

L.H 243. 3°  F. 

Suction  at  compressor  R.H 14 . 34°  F. 

L.H i5.2o°F. 

At  cooler 9 . 29°  F. 

Before  expansion  valve 77 . 91°  F. 

Brine  at  inlet  to  cooler 22 . 73°  F. 

Brine  at  outlet  from  cooler 13 .02°  F. 

Engine  room 64 . 80°  F. 

Ammonia  receiver  room 73 .46°  F. 

Outside  atmosphere 24. 79°  F. 

R.H.  water  jacket 180.7°  F- 

L.H.  water  jacket 168.45°  F. 

Revolutions  in  i5-minute  compressor 514. 7 

Brine  pump 426 . 85 


402  ELEMENTS  OF  REFRIGERATION 

Specific  heat  of  brine o. 678 

Weight  of  brine  per  revolution 41-15  lb. 

Pounds  of  liquid  ammonia  in  15  minutes 233-9 

Pressures :     Suction  at  cooler 20.46 

at  compressor 20.04 

at  condenser 187 . 27 

Steam  at  engine 81 . 96 

Barometer 14 . 95 

M.E.P.:     Headend 36.56 

Crank  end 37 . 09 

I-H.P 5^57 

Tons  of  refrigeration  by  brine 37 . 01 

Equivalent  tons  with  2o-lb.  suction 36.97 

I.H.P.  per  ton i .  42 

Size  of  compressor 15X22   (single  acting) 

Size  of  engine 22  X22    (3!  piston  rod) 

TEST  or  Two  DE  LA  VERGNE  STANDARD  HORIZONTAL    RE- 
FRIGERATING MACHINES,  DATE  OCT.  27,  1910 

Temperatures:  Ammonia  discharge 245 .80°  F. 

Ammonia  suction  at  brine  coolers .  .  5 .  o°  F. 

Ammonia  before  expansion  valves.  8. 14°  F. 

Brine  at  inlet 6 . 20°  F. 

Brine  at  outlet 17.6°  F. 

Revolutions  of  compressors 43-5 

Pressures:     Suction 16 .  23 

At  condensers < . .  165 . 50 

Total  horse-power 517 . 88 

Tons  of  refrigeration 373 . 23 

I.H.P.  per  ton 1.398 

Size  of  compressors  double  acting.  .  i8j//X33// 

Size  of  engine 22  &  44 X33 

Volumetric  eff. :  Apparent 95 . 38 

True 82.15 

Rated  capacity,  two,  275  tons,   550 
tons 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     403 

TEST  OF  KROESCHELL  BROS.  ICE  MACHINE  Co.'s  CO2  COM- 
PRESSOR, DATE  AUGUST  9,  1907 

Compressor,  double  acting,  horizontal. 

Bore 138  M/M  =  s&" 

Stroke 508 

Piston  rod 58 

Speed 65  R.P.M. 

Compressor  gas  displacement 54,914.6  cu.in.  per  min. 

Condenser  pressure 65  atm. 

Evaporating  pressure 23  atm. 

Evaporating  temperature ;  5°F. 

Water  temperature  condenser  inlet 53°  F. 

Water  temperature  condenser  outlet  ...  81°  F. 

Temperature  of  brine  cooler  inlet 25 . 9°  F. 

Temperature  of  brine  cooler  outlet 17°  F. 

Quantity  of  brine  pumped  per  hour ....  1000  cu.ft. 

Strength  of  brine .  .  . 26°  Beaume 

Estimated  loss  in  brine  tanks  and  cooler  10% 

Amount  of  refrigeration 50. 76  tons 

Indicated  power  at  engine .  . 67 . 25  H.P. 

Indicated  power  at  compressor 51 . 3  H. P. 

Compressor  gas  displacement  per  ton  per 

per  min 1082  cu.in. 

Horse-power  -v-  cooling  effect  =  i  .010 

H.P.  per  ton  of  refrigeration. 

TEST  OF  VOGT  ABSORPTION  PLANT 

Aqua  ammonia  pump 5l  X 12 

Average  speed  pump 22  R.P.M. 

Temperature:  Brine  inlet ,15°  F. 

Brine  outlet 13°  F. 

Ammonia  at  condenser 105°  F. 

Liquid  from  condenser 78°  F. 

Strong  aqua  to  rectifier 89°  F. 

Strong  aqua  from  rectifier 120°  F. 

Strong  aqua  from  exchanges 189°  F. 


404  ELEMENTS  OF  REFRIGERATION 


Weak  aqua  from  cooler  ......................     89    F. 

Cooling  water  ..............................     65°  F. 

Cooling  water  from  condenser  ................     72°  F. 

Cooling  water  from  absorber  .................     88°  F. 

Cooling  water  from  weak  aqua  cooler  .........  117° 

Strong  aqua  at  60°  F  ........................     26^°  Beaume 

Weak  aqua  at  60°  F  ........................     23!  °  Beaume 

Total  cooling  water  per  min  ..................  252  gals. 

Ice  per  ton  of  coal  ........  -.  .................     10.3  tons 

TEST  OF  WESTINGHOUSE-LEBLANC  REFRIGERATING  MACHINES, 
DATE  AUG.  4TH  AND  5TH,  1916 

Barometer  ..............................  29.  17" 

Temperature  atmosphere  .................  86°  F. 

Live  steam  pressure  ......................  200  Ibs.  per  sq.in. 

Vacuum:    ist  ejector  .....................  29 

2d  ejector  .....................  28  .  95 

Condenser  .................  ....  27.80 

Temperature:   Condensing  water  inlet  ......  82  .  5°  F. 

Condensing  water  outlet  .....  92°  F. 

Brine  inlet  .......  :  .........  18  .40°  F. 

Outlet  ....................  15.00°  F. 

Weight  of  brine  per  hour  .................  19826 

Specific  heat  brine  ........................  833 

B.t.u.  of  refrigeration  per  hour  ............  56,202 

Tons  per  twenty-  four  hours  ..............  :  4  .  60 

Loss  by  radiation  .........................  37 

Total  loss  ...............................  5  .05 

Steam  and  vapor  condensed  per  hour  .......  1125 

Vapor  per  hour  ..........................  61 

Steam  per  hour  ..........................  1064 

Tons  of  refrigeration  per  ton  of  coal  at  8  Ibs.  of  steam  per  pound 
of  coal: 


3       1.596 
1064  X?£ 

8X2000 


COSTS  OF  INSTALLATION  AND  OPERATION  TESTS     405 

TEST  OF  WESTINGHOUSE-LEBLANC  APPARATUS  FOR  COOLING 

WATER.     MARCH  24,  1915 

Barometer 29 . 18 

Vacuum  in  ist  ejector 28.91 

Vacuum  in  condenser 27 . 40 

Steam  pressure  (gauge) 125 

ist  ejector 112.5 

2d  ejector 110.5 

Quality 98.7% 

Temperatures : 

Water  to  be  cooled  (brine  ordinarily) 

at  inlet 40.5°  F. 

at  outlet. 34 . 9°  F. 

Steam,  line 357-3°  F. 

Atmosphere 69 .  i  °  F. 

Condenser,  top 155 . 5°  F. 

Condensate 89. 7°  F. 

Circulating  water  inlet 79.9°  F. 

Outlet. 89.7°  F. 

Weights  per  hour: 

Water  to  be  cooled .  .  101,320 

Circulating  water 450,000 

Condensed  steam 2513 

Heads  pumped  against 67 . 2  ft. 

Power  brine  pump 8 . 83  H.P. 

Condenser 35-7  H.P. 

Refrigeration 567,392  B.t.u.  per  hr. 


406 


ELEMENTS  OF  REFRIGERATION 

TESTS  OF  HART  COOLING  TOWER 


TEMPERATURE. 

Water. 

Air. 

Gallons 

Rel.  Hu- 

Above 

Below 

Wet 

Atmos- 

Enter- 

Reduc- 

Dry 

Wet 

Bulb. 

phere. 

ing. 

Leaving. 

tion. 

Bulb. 

Bulb. 

78 

74 

4 

88 

72 

2 

14 

600 

41 

77 

7i 

6 

88 

71 

O 

17 

600 

39 

81 

76 

5 

88 

.  74 

2 

12 

600 

46 

79 

76 

3 

84 

74 

2 

8 

600 

57 

82 

75 

7 

81 

73 

2 

6 

600 

64 

75 

69 

6 

7i 

67 

2 

2 

600 

78 

108 

76 

32 

87 

73 

3 

II 

1800 

46 

in 

73 

36 

76 

66 

7 

3 

1800 

55 

1  08 

76 

32 

81 

72 

4 

5 

1800 

60 

109 

78 

3i 

79 

73 

5 

i 

1800 

7i 

1  08 

74 

34 

74 

69 

5 

0 

1800 

74 

83 

68 

15 

77 

62 

6 

9 

3000 

4i 

CHAPTER  X 
PROBLEMS 

THIS  chapter  is  devoted  to  problems  illustrating  the  appli- 
cation of  the  text.  They  are  typical  problems,  and  the  student 
is  urged  to  consider  them  as  illustrating  principles  so  that 
other  problems  of  similar  nature  may  be  solved  in  the  same  man- 
ner. Certain  problems  are  solved  for  a  given  set  of  conditions 
and  if  these  conditions  change  the  results  will,  of  course,  differ 
from  those  obtained.  The  general  problems  of  design  are  repe- 
titions of  certain  fundamental  problems  and  it  has  been  the  aim 
of  the  author  to  include  these  fundamentals  in  this  set.  The 
data  to  be  used  in  actual  problems  must  be  obtained  for  the 
particular  locality. 

Problem  i.  Find  the  best  thickness  of  cork  insulation  for 
an  8-in.  wall  on  a  room  which  is  to  be  held  at  20°  F. 

Cork  thicknesses  possible:  2  in.,  3  in.,  two  2  in.,  2  and  3  in., 
two  3  in.,  etc. 

Cost  of  i  sq.ft.  of  cork  installed  (page  346) : 

2  in 25  cts. 

3  jn 3°  cts. 

4  in 40  cts. 

5  in. . : 50  cts. 

6  in 60  cts. 

Value  of  i  cu.ft.  of  storage  space,  per  mo 5  cts.  (p.  215) 

Cost  of  i  ton  of  refrigeration 40  cts.  (p.  376). 

Average  outside  temperature  per  year 48°  F.  (Fig.  166). 

Fixed  charges  (p.  379). 

Interest 8% 

Taxes i% 

Insurance i% 

Depreciation 3% 

Repairs 2% 

Total 15% 

407 


408  ELEMENTS  OF  REFRIGERATION 

Coefficient  for  8-in.  walls  with  plaster  ........  ^"  =  o.37(p2ii) 

C  for  cork  .............................  0.022 

C  for  plaster  ...........................  o  .  46 

For  completed  walls  the  effect  of  additional  layers  of  materials 
may  be  computed  in  the  following  way:        .. 


K'  =new  constant; 

K  =  former  constant  for  wall; 

/  =  thicknesses  of  new  layers; 

C  =  coefficients  of  new  layers. 

(a)  K  for  8"  brick,  2"  cork,  i"  plaster. 

K'  =  -  -=0.095. 

1     ,          2         +       T 
0.37     12X0.022     12X0.46 

(b)  K  for  8"  brick,  3"  cork,  i"  plaster. 

K'  =  -  =0.070. 


0.37     12X0.022     12X0.46 

(c)  K  for  8"  brick,  4"  cork,  i"  plaster  (2",  J",  2",  %").} 

^  =  0.055- 

(d)  K  for  8X/  brick,  5"  cork,  i"  plaster  (2",  \"  ,  3",  J"). 

^  =  0.046. 

Heat  Loss  per  Year  in  Tons  of  Refrigeration  per  square  foot. 
(a) 


(V)  0,81  X          =  o.6o  ton; 

0.095 


PROBLEMS  409 


(c)  0.81X^^=0.47  ton; 

0.095 


(d)  0.81  X-  =0.39  ton. 

Cost  of  Refrigeration  per  Square  Foot  per  Year. 

(a)  0.81X40  =  10.324; 

(b)  0.60X40=  0.240; 

(c)  0.47X40=  0.188; 

(d)  0.39X40=  0.156. 
Cost  of  Space  Required  per  Year. 

(a)  —  X  1X0.05X12  =0.120; 


(b)  —  X  1X0.05X12=0.180; 

12 

(c)  —  X  1X0.05X12  =0.240; 
(£)  -  X  i  Xo.o5  X  1  2  =  0.300. 

Yearly  Cost  of  Insulation  Investment  per  Year, 

(a)  0.25X0.15=10.037; 

(b)  0.30X0.15=  0.045; 

(c)  0.40X0.15=  0.060; 

(d)  0.50X0.15=  0.075. 

Total  Yearly  Cost. 

(a)  0.324+0.120+0.037=10.481; 

(b)  =  0.456; 

(c)  =   0.488; 

(d)  =  0.521. 


410  ELEMENTS  OF  REFRIGERATION 

From  the  above  it  is  seen  that  for  the  assumed  conditions 
the  3-in.  thickness  is  the  best.  If  conditions  (assumed  data) 
be  changed,  a  different  result  will  be  obtained.  If  space  is 
worth  2\  cents  per  cu.ft.  per  month,  a  wall  made  up  of  two  2-in. 
boards  would  be  best. 

Problem  2  Find  the  space  required  to  store  the  following: 
180,000  doz.  eggs,  25,000  bu.  potatoes,  200,000  Ibs.  butter, 
200,000  Ibs.  cheese,  25,000  bu.  apples,  400,000  Ibs.  beef,  200,000 
Ibs.  mutton,  200,000  Ibs.  pork,  20,000  Ibs.  poultry,  500  crates 
celery,  2000  bbls.  vegetables,  2000  boxes  oranges  and  lemons. 

(a)  Size  Egg  Room. 

,  180,000     , 

No.  of  cases  =  —        -  =  6000  ; 

30 

Volume  of  cases  =  6000X2^  =  1  3,  500  cu.ft.; 
Height  of  piles  =  6  ft.; 


Net  floor  area  =  =  225o  sq.ft.; 

6 

Allow  |  for  aisles. 

Total  floor  area  =  2  250X1  =  337  5  sq.ft. 

(b)  Size  Potato  Room. 

No.  of  barrels  =  —  -  =  10,000  bbls.  ; 
2-5 

Space  required  =  10,000  X  5  =  50,000  cu.ft.  ; 
Height  of  piles  =  8  ft.; 


Net  floor  area  =  =  6250  sq.ft.; 

o 

Allow  i  for  aisles. 

Total  floor  area  =  6250X1  =  7812  sq.ft. 

(c)  Size  Butter  Room. 


No.  of  tubs  =  =  4000; 

50 

Space  =  4000  X  2  =  8000  ; 
Height  of  piles  =  6  ft. 


PROBLEMS  411 

Net  floor  area  =  —  —  =  1  143  =  1  200  sq.ft.  ; 

Total  floor  area  =  1400  sq.ft. 

(d)  Size  Cheese  Room. 

Same  as  (c),  1400  sq.  ft. 

(e)  Size  Apple  Room. 

Same  as  (b),  7812  sq.ft. 

(/)   Size  of  Beef  Room. 

No.  of  halves  of  beef  =  -  —  -  -  X  2  =  1070. 

750 

Assume  these  to  be  hung  at  i8-in.  intervals  and  3  ft.  apart. 
Floor  space  =  1070  X  i^  X  3  =  4800  sq.ft. 

(g)  Size  of  Mutton  Room. 

Assume  carcass  weighs  60  Ibs  per  cu.ft.  in  piles  and  that 
piles  are  4  ft.  high  with  aisles  occupying  one-quarter 
space. 


Floor  space  =  —^  -  X-  =  1  100  sq.ft. 
60X4      3 

(h)  Size  of  Pork  Room. 

Same  as  (g),  noo  sq.ft. 

(i)   Size  of  Poultry  Room. 

Same  as  (g),  noo  sq.  ft. 

(j)   Size  of  Celery  Room. 

Total  volume  =  500  X  10  =  5000  cu.ft.  ; 
Height  of  piles  =  8  ft.; 


Net  floor  area  =         =  625  sq.ft.; 

8 

Allow  ^  for  aisles. 

Total  floor  area  =  625  X  f  =  940  sq.ft. 


412 


ELEMENTS  OF  REFRIGERATION 


(k)  Size  of  Vegetable  Room. 

Space  =  2000  bbls.  X  5  =  10,000  cu.f t. ; 
Height  piles  =  8  ft.; 

10,000 


Net  floor  area  = 


8 


=  1250  sq.ft.; 


Allow  i  for  aisles. 

Total  floor  area  =  1250  Xf  =  1600  sq.ft. 

(/)    Size  of  Orange  Room.     .- 

Space  =  2000  X4  =  8000  cu.ft. ; 

Height  =  5  ft; 

Net  floor  space  =  1600  sq.ft.; 

Allow  i  for  aisles. 

Total  floor  area  =  2000  sq.ft. 

The  layout  shown  in  Fig.  185  is  suggested  for  this  problem. 
The  height  of  the  stories  would  be  10   ft.  in   the  clear.     The 


5th  Floor  6th  Floor 

FIG.  185. — Typical  Warehouse. 


height  of  the  building  with  a  4-ft.  basement  and  a  5-ft.  attic 
would  give  a  total  height  of  75  ft. 


PROBLEMS  413 

Problem  3.  Find  the  probable  amount  of  refrigeration  for 
the  plant  in  Problem  2,  assuming  that  all  goods  are  received 
at  70°  F.  and  that  90°  F.  is  the  warmest  weather.  Insulation: 
Main  walls,  8-in.  brick  with  two  3-in.  thicknesses  of  cork  at- 
tached with  plaster  and  plaster  finish.  Partitions:  8-in.  tile 
with  plaster  and  2  ins.  of  cork  on  one  side,  plastered.  Floors 
at  second  story  and  ceiling  of  sixth  floor:  second  figure,  Fig.  108; 
other  floors:  brick  arches  with  ^  =  0.25. 

(a)  Temperature  of  Rooms. 

Eggs,  31°  F.;  Meat,  30°  F.; 

Cheese,  32°  F.;  Apples,  potatoes,  vegetables,  36°  F.; 

Butter,  1 5 °  F. ;  Oranges,  lemons,  40°  F. ; 

Poultry,  20°  F. ;  Celery,  34°  F. 

(6)  K's  for  Walls. 

K  for  walls  (from  p.  211)     =0.039; 
K  for  partitions. 

K  = I =0.081. 


0.21  12  2Xl2 

0.022         0.46 

0.21  for  tile  with  plaster,  p.  211; 
0.022  from  p.  193  for  compressed  cork; 
0.46  from  p.  193  for  plaster. 


K  for  floors. 

K  =  0.062  p.  2ii  (second  story); 

=  0.25   assumed   for   hollow   arch   bricks   without 

insulation  (3d  to  5th) ; 
=  0.030  (p.  211),  ceiling,  top  floor. 

(c)   Heat  Loss  through  Walls,  Floors,  Ceilings,  Partitions. 
Heat  loss  from  rooms  in  B.t.u.  per  hour. 


414  ELEMENTS  OF  REFRIGERATION 

FIRST  FLOOR 
Holding  room : 

Wall,  35X10 X  (90-30)  Xo.039  =          820 

Partitions  (45  +  154- 10+20+35)  XioX 

(90 — 30)  X  0.08 1  =        67  50 

Floor  =  oo 

Ceiling,  35X35X(36-3o)  Xo.o62  1 
loX  15  X  (40-30)  Xo.o62j 

8119 
Total  for  first  floor  8119 

SECOND  FLOOR 
Celery  room: 

Walls  (55+35)  XioX (90-34)  Xo.039  =        1965 

Partitions  [35 XioX (36 -34) +  20 XioX 

(90-34) +35  XioX  (40-34)1X0.081       =        1134 
Floor  35X55 X (90  — 34) X 0.062  =        6684 

Ceiling  [35X35X(3i-34)+35X2oX 

(i5-34)]Xo.25  =     -4244 

5539 
Vegetable  room: 

Walls  (55+35) XioX (90-36) Xo.039  =  1895 
Partitions  [3 5 XioX (34  —  36) +  20 

X  10(90-36) +35X10(40-36)1X0.081  =  931 
Floor  [35  X35X (30-36) +20X35(90-36)] 

X  0.062  =  1888 

Ceiling  (35X55)  X(3i-36)Xo.25  =  -2406 

2308 

Orange  room  I: 

Walls  (55+35)  XioX (90-40)  Xo.039  =        1755 

Partitions  [3 5 XioX (36  —  40) +  20X10 

X(90-4o)+35Xio(4oX4o)]Xo.o8i  =          697 

Floor  [(35X45X90-40) +  10X15(30-40) 

+  20  X 10  X  (90 -4o)]Xo.o62  =        5410 

Ceiling  35  X55X  (32 -40)  Xo.25  =     -3850 

4012 


PROBLEMS  415 

Orange  room  II . 

Walls  (55+35)  XioX (90-40) Xo.039  1755 

Partitions  [35 XioX (34  —  40) +  20X10 

X  (90-40)  +35  X 10  X  (40-40)10.081  640 

Floor  35 X55X (90-40)  Xo.o62  5964 

Ceiling  [35  X3$X (15-40)4-29X3$ 

X  (20-40)1x0.25  =-11,156 

-2797 
Total  for  second  floor  9062 

THIRD  FLOOR 
(In  the  same  manner  as  before.) 

Egg  room , 6,760 

Butter  rocm 22,642 

Cheese  room 5,3*8 

Poultry  room 7,128 

Total  for  third  floor 41,848  B.t.u. 

FOURTH  FLOOR 

Beef  room .  12,433 

Mutton  room 4466 

Pork  room —  742 

Total  for  fourth  floor J6,i57  B.t.u. 

FIFTH  FLOOR 
Total  for  floor 22,632  B.t.u. 

SIXTH  FLOOR 

Total  for  floor 23,554  B.t.u. 

Totals: 

First  floor 8,119 

Second  floor 9,062 

Third  floor 41,848 

Fourth  floor J6,i57 

Fifth  floor 22,632 

Sixth  floor 23,554 

122,372 


r  r>         •     J  , 

2  ons  Required:  — —  =  10.2 «;, 

60X199.2 


416  ELEMENTS  OF  REFRIGERATION 

(d)  Heat  from  Goods.     The  greatest  amount  received  at  one 
time  will  have  to  be  assumed  together  with  the  time  required  to 
reduce   the  goods   to   warehouse   conditions.     The   cooling  is 
assumed   to    take   place  in  forty-eight    hours.     The   greatest 
amount  received  at  any  one  time  is  assumed  to  be  the  following: 

Beef,  40,000  Ibs. ;  Butter,  6000  Ibs. ; 

Mutton,  15,000  Ibs.;  Poultry,  2000  Ibs.; 

Pork,  25,000  Ibs.;  Apples,  300  bbls.; 

Eggs,  300  crates;  Potatoes,  200  bbls. 

Heat  Removed  (see  p.  215): 

From  B eef:  40,0001X70  —  30)  X  0.70 +90]       =  4,720,000 

Mutton:  i5,ooo[(7o— 3o)Xo.67+Qo]=  1,752,000 

Pork:  25,0001(70-30)  Xo.5o+9o]      =  2,750,000 

Eggs:  (30oX5o)[(7o-3i)Xo.76]        =  444,600 

Butter:  6ooo[(7o—  i5)Xo.6o-h84]      =  702,000 

Poultry:  2ooo[(7o  —  20)  Xo. 80+102]  =  284,000 

Apples:  (300X1 50) [(70-36)  X 0.92]  =  1,407,600 

Po tatoes:  (200^X1 50) [(70  — 36)  X 0.80]  =  816,000 

Total  12,876,200 

rr  T>  '        1  I2,876,2OO 

Tons  Required:  —  =  22.4. 

48X60X199.2 

(e)  Heat  from  Lights   (p.  341). 

In  rooms  55X35  there  would  probably  be  ten  20- watt 
lamps.  If  six  rooms  are  being  used  at  one  time  the  heat  from 
these  will  be 

„,      10X20X6X3.41 
Te  =  —      —-—^—  =  0.34  ton. 
199.2X60 

(/)  Heat  from  Men  (p.  214). 
Assume  10  men  working  at  one  time. 

„,       10X1150 
Tm= —       ——=0.96  ton. 
199.2X60 

(g)  Leakage  through  Doors.  This  is  a  difficult  quantity  to 
estimate  and  if  the  assumption  is  made  that  K  =  2  and  that  the 


PROBLEMS  417 

door  area  is  8x8  and  that  10  of  these  may  be  open  at  one  time, 
the  following  results: 


= 

60X199.2 

Totals: 

Walls  ..........................    10.25 

Goods  .........................   22.40 

Lights  ................  ..........  34 

Men  ............................  96 

Leakage  .......................     6.20 


40.15 

If  33%  excess  is  allowed  for  safety  the  total  will  be  54  tons. 
To  check  this,  various  general  rules  will  be  used. 

Volume  of  Building: 

cu.ft. 


From  Peterson's  rule,  on  p.  256,  using  20,000  cu.ft.  as  the 
average  size  of  the  room  and  30°  as  the  average  temperature: 


[20  oooH 
=  4000; 
5000  J 


Tons  required  =  -- — —  =  104  tons. 
4000 

From  average  rule  on  p.  256: 

Tons  required  =  ----—  =  140  tons. 
3000 

The  difference  in  these  results  is  due  to  the  assumptions 
made.  In  the  first  case  the  insulation  is  heavy  and  the  time  to 
cool  goods  is  moderately  long.  If  this  time  were  made  less  and 
the  insulation  poorer,  the  tonnage  would  be  increased.  In  the 
general  rules,  there  is  no  specific  value  for  these  items. 

In  this  problem  two  30- ton  machines  should  be  installed. 


418  ELEMENTS  OF  REFRIGERATION 

Problem  4.     Find  the  amount  of  radiation  to  be  placed  in 
the  room  for  beef  storage. 

Heat  from  walls  =   12,433  B.t.u.  per  hr. 


Heat  from  beef  =      -  =  100,000  B.t.u.  per  hr. 
48 

Heat  from  lights  =  20X20X3.  41  =      1364  B.t.u.  per  hr. 

Heat  from  men  =  5X1150  =      5750  B.t.u.  per  hr. 

Heat  from  door  =  64X2X60  =      7680  B.t.u.  per  hr. 


127,227  B.t.u.  per  hr. 
(a)  Direct  Expansion. 

tr  =30°  F.; 
ta  =20°F.; 
#  =  5  (p.  244); 


Using  extra  heavy  2-in.  pipe,  i.  608  ft.  of  length  will  give  i  sq.ft. 
Total  Length  =  2544X1.  608  =4100  lin.  ft. 
From  rules  on  pp.  255  and  256  the  following  is  obtained: 

Volume  of  room  ...............  45>5oo 

Temperature  ...........  .......  30°  F. 

Allow  f  of  25  cu.ft.  per  lin.  ft.  on  account  of  first  freezing. 
'  -700  lin.  ft  " 


Allow  f  of  35  sq.ft.  per  1000  cu.ft.  to  allow  for  freezing  in 
forty-eight  hours- 


Surface  =    -xx35  =  2350  sq.ft. 

Lin.  ft.  =  2350X1.608=3790  lin.  ft. 

Amount  allowed  for  room,  4000  lin.  ft.  This  will  be  arranged 
in  eight  coils  37  \  ft.  long  and  four  coils  25  ft.  long.  Each  coil 
will  be  five  pipes  high  and  two  pipes  wide. 


PROBLEMS  419 

(b)  Brine.     Surface,  first  method,  using  7^°  difference  in 
place  of  10°  will  require  6100  lin.  ft. 


Levey's  table:      Lin.  ft.  =-       =  4000  lin.  ft.; 


Schmidt's  table:  Lin.  ft=     °     X-X  50X1.6  =  5460  lin.  ft. 

IOOO         2 

Amount  to  be  used,  6000  lin.  ft. 

Problem  5.  Find  the  length  of  2-in.  brine  pipe  with  a  drop 
of  5°  and  a  mean  temperature  difference  of  7^°  F.  between  room 
and  brine,  assuring  a  4-ft.  per  second  velocity  of  brine. 

Internal  area — standard  2"  pipe 3-355  sq.in. 

Outside  circumference — standard  2"  pipe .•  •  •  •  7461  in. 

Brine,  sp.gr 1.119 

Specific  heat 0.8 

K : 5.0 

From  (19)  p.  259: 

:. 119X0.8X5 
=4260  ft. 


In  table  on  page  255  it  is  noted  that  Levey  suggests  that 
these  coils  be  made  275  ft.  long.  If  such  is  done  there  will  be 
different  conditions  from  those  noted:  First,  the  velocity  must 
be  much  less  than  4  ft.,  and  second  the  temperature  drop  will 
be  less  than  5°  F.  Of  course,  if  K  is  taken  as  10  instead  of  5, 
there  will  be  a  decrease  in  length.  If  i  ft.  per  second  is  used 
as  velocity,  and  the  drop  is  taken  as  2°,  although  the  tempera- 
ture drop  is  7^°,  and  if  K  is  used  as  10,  the  length  is  found  to 
be  about  215  ft. 

=  2i    ft. 


420  ELEMENTS  OF  REFRIGERATION 

Problem  6.  Find  the  velocity  of  brine  in  a  2-in.  coil,  190  ft. 
long,  if  the  mean  temperature  difference  is  5°  F.,  K  =  $,  and 
temperature  drop  is  5°  F. 

13  =  190X^^X5X5  =  2^^X^X3600X62.4X1.  119X0.8X5 
12  144 

^  =  0.127  ft.  per  sec. 

Problem  7.  Find  the  amount  of  ammonia  which  will  be 
evaporated  in  a  2-in.  coil,  190  ft.  long,  of  extra  heavy  pipe,  if  the 
ammonia  is  at  60°  F.  before  throttling  it  to  20°  F.,  and  the 
temperature  difference  is  10°  F. 

Heat  from  Pipe  =  190  X—  —  X5X  10  =  5900  B.t.u.  per  hr. 

Heat  for  i  Ib.  of  Ammonia  =  (ii  —  is)  =  512.8(75)  p.  69. 
i  for  60°  F.  and  x  =  o  =  30.9 
i  for  20°  F.  and  x  =  i  =  543.7 


Pounds  of  ammonia  per  hour  =         .  =  11.5  Ibs. 

512.8 

Quality  of  ammonia  after  throttling  to 

o         30.9  —  (  —  12.6) 
20,*  =  ^-  —=0.078. 

556.3 
Specific  volume  after  throttling 

=  0.078  X  5.92  +0.922  Xo.0244  =  0.484. 
Velocity  of  mixture  in  2-in.  pipe  at  entrance  : 

w  =  —  i23  -  ^—x  144  =  0.078  ft.  per  sec. 


If  longer  pipes  are  used  a  greater  quantity  will  be  admitted 
and  a  higher  velocity  will  be  used. 

Problem  8.  Find  the  amount  of  air  to  be  admitted  in  an 
indirect  system  for  the  data  of  Problem  4  during  the  time  of 
filling.  Find  the  surface  required  in  bunker  coils. 


PROBLEMS  421 

Heat  removed  per  hour  =  127,2 2 7  B.t.u.; 
Temperature  of  room,  30°  F.; 
Assumed  temperature  of  air,  20°  F. 

127  227 

Amount  of  air  per  minute  =  —   — — — '——-  =  10,602  cu.ft. 

10X0.02X60 

This  assumes  that  air  retains  the  same  amount  of  moisture. 
Use  i-in.  pipes  for  bunker  coils.     Assume  velocity  of  air  900 
ft.  per  minute. 

Area  through  clear  space  in  bunker 

10,602 


900 


X 144  =  1700  sq.in. 


If  pipes  are  6  ft.  long  and  i  in.  is  allowed  between  pipes,  the 
number  of  sections  will  be 

1700 
-  =  24. 

72 


=6.03,  (14),  p.  256. 
Air  is  cooled  from  30  to  20  with  ammonia  at  15°  F. 

Mean  A/  =  ,      ,,=Q.I. 

fog,¥ 

Surface    =  I27>227  =232050.  ft. 
9.1X6.03 

or  2320X2.904  =  6750  lin.  ft. 


Lines  of  pipe  per  section  =  —  '-—  =47. 

24X6 

This  excessive  number  of  lines  and  surface  is  due  to  the  small 
difference  of  temperature  assumed.  If  a  greater  difference  in 
temperature  were  used,  the  coil  surface  would  be  smaller,  but 
the  cost  of  compression  would  be  greater,  as  a  lower  back  pres- 
sure would  be  needed. 

This  problem  has  not  considered  any  change  in  moisture 
content.  If  this  were  taken  into  consideration,  more  surface 
would  be  required.  The  problem  of  heat  and  surface  required 


422  ELEMENTS  OF  REFRIGERATION 

when  there  is  a  change  of  moisture  content  is  given  in  Prob- 
lem 25. 

Problem  9.     Find  the  size  of  ducts  for  air  of    Problem  8 
together  with  pressure  drop,  size  of  fan,  and  power  required. 

Velocities  in  System  (p.  248) : 

In  register 300  ft.  per  min. 

In  branches 800  ft.  per  min. 

In  main 1200  ft.  per  min. 


Size  of  main=I°^=S.S  sq.ft.,  4/X2.2/. 

Assume  main  80  ft.  long  with  5  bends,  4'  X2.2r. 
Assume  branch  20  ft.  long  with  3  bends,  2'  X  i'. 

(_3JLO\2 

Loss  in  grill       =  o.8x\?°     =  Q-31   (p.  250). 

64-3 

2O  (8_Q_0\2 

Loss  in  branch  =o.02X—        -X  Vf°     =0.83  (p.  240). 
4X0.33      64.3 


(.800)2 

Losshi3bends  =  3Xo.i5X^   -  =  1.24. 

°4-3 

g0       (i  2.0.0.)  2 

Loss  in  main       =o.o2X—  — 

4X0.71     64.3 

8.8 


(  i2.AO.N2 

Loss  in  5  bends  =  0.15  X  5  X^-^  =  4.66 

04-3 


2 

Loss  in  47  lines  of  pipe  =  47  X  0.4  X^^  —     =  65.6 

64-3 

(300)  2 

Velocity  head  at  end     =  J    '  =  0.39 

04-3 

Total  loss  76.54  ft.  of  air. 


PROBLEMS  423 

Oz.  pressure  =          =0.696  (p.  250). 


no 


Inches  of  water  =0.696X1.73  =  1.20. 

Dynamic  pressure  for  Sirocco  fan  (p.  251)=°'  9   =0.977  oz« 

0.712 


Equivalent  tabular  volume  for  i  oz.  =  io,6o2A/-J —  =  10,750. 

\o.977 

No.  6  fan  is  the  nearest  fan  in  the  table. 


Speed  =38lXJ™  =  376. 


Discharge  =  1 1, 300  XA/-^^  =  11,150. 

\  i.ooo 


Power 


This  fan  is  slightly  too  large,  but  using  tabular  values  only  it 
is  the  one  which  must  be  selected. 

Problem  10.  Find  the  size  brine  main,  size  of  pump,  and 
power  to  pump  brine  for  warehouse. 

For  60  tons  capacity  and  10°  drop  in  brine,  the  weight  of 
brine  to  be  circulated  per  minute  is  given  by  (18)  p.  259. 

M6Xo.8X  10  =  60X199.2. 
Mb  =  1498  Ibs. 

Volume  per  min.  = — =  21.44  cu.ft.  =  160  gal.  per  min. 

62.4X1.119 

Q  T    A 

Area  main  =  ~    —  X 144  =  12. 9  sq.in. 
60X4 

Use  4-in.  pipe.  Area,  12.65  sq.in.  This  gives  a  velocity  of 
4.1  ft.  per  sec. 

Duplex  pump  size  to  discharge  brine  at  45  cycles  per  minute. 


424  ELEMENTS  OF  REFRIGERATION 

Assume  8-in.  stroke. 

21.44X1728 
45X4X8    =  2S' 

Diameter,  5!  in. 

Use  6  X  8-in.  brine  end  to  pump. 

To  find  power  to  drive  brine  through  warehouse  it  would  be 
necessary  to  lay  out  all  lines,  branch  circuits  and  compute  losses 
in  various  parts.  To  find,  the  approximate  power  it  will  be 
assumed  that  the  4-in.  line  extends  to  the  top  of  the  building  and 
back  again  with  200  feet  of  pipe  and  eight  right-angle  bends,  and 
the  longest  branch,  near  end,  is  400  feet  of  2-in.  pipe  with  thirty 
right-angle  bends.  The  velocity  is  0.127  ft.  per  second  in  the 
branch  and  4.  i  f  t.  per  second  in  the  main.  The  main  has  branches 
taken  off  from  it  at  intervals  and  is,  therefore,  equivalent  to  a 
main  of  length  equal  to  one-third  of  the  length  on  line. 

From  p.  260: 


,  0.021; 

/=/—         —  —  H7  =0.065. 
(0.17X0.127)* 


.. 
0.33       64.3  0.33      64.3  0.167 

2.2    ft. 


. 

64.3  2  64.2 

There  is  no  head  lost  in  forcing  the  brine  to  top  of  the  system, 
as  the  pipe  is  full.  The  slight  difference  in  density,  due  to  10° 
difference  in  temperature  in  ascending  and  descending  pipes,  is 
neglected. 

Total  hydraulic  work  =  2.  27X1498  =  3410  ft.lbs.  per  min. 

Assuming  60%  for  the  mechanical  efficiency  of  pump,  the 
power  required  to  drive  pump  is 

3410  x-[- 

I.H.P.  =  -  —  =  0.172  H.P. 
33,000 


PROBLEMS  425 

Problem  n.     Find  the  size  of  supply  main  for  liquid  am- 
monia and  return  main  for  vapor  for  warehouse. 

Total  ammonia  per  min.  =—         ^     =  23.3  Ibs.  (See  Prob.  7.) 

Volume  of  liquid  at  60°  F.  =  23.3  Xo.o26og=  0.609  cu.ft. 

0.600 

Area  pipe          =—     —  X  144  =  0.365  sq.m. 
4X00 

Diameter  =  f". 

Use  i"  extra  heavy  pipe. 

Volume  of  vapor  at  15°  =  23.  3X6.  583  =  153  cu.ft. 

(a)  From   Velocity  Considerations. 

Assume  velocity  60  ft.  per  sec.  (p.  257). 

Area  =  —^4^X144  =  6.1  sq.in. 
60X60 

Use  extra  heavy  3  -in.  pipe. 

(b)  From  Pressure  Drop  Considerations. 

Assume  J  Ib.  drop  in  50  ft.  of  pipe  (p.  257). 


d      o.i5i9Xd 
Use  3"  for  d  within  bracket. 


d  =3.16. 

Use  $\"  extra  heavy  pipe. 

Problem  12.  Find  the  size  of  a  freezing  tank  for  a  50-ton 
plant  using  3oo-lb.  cans. 

Size  of  can  from  p.  290:  1  1|  X  22^  at  top,  io|  X  21^  at  bottom, 
45  in.  length  over  all,  44  in.  length  inside. 

Surface  transmitting  heat  for  42  in.  water  depth 


=  20.83  Sq.ft. 

Heat  per  hour  with  20°  brine  and  a  coefficient  of  3.3  B.t.u. 
=  20.83  X(32  -20)  X3-3  =826. 


426  ELEMENTS  OF  REFRIGERATION 

Heat  from  can  =  3001144.3  +  (40  —  32)1=48,390  B.t.u. 
(Temperature  of  water  from  cooler,  40°;  p.  308.) 
(Temperature  of  ice  20°  F.) 


Hours  to  remove  heat  =  -~-  =58.5. 
826 


(3)  P-  3°4' 


-2 


Time  to  freeze  =  —  —  ^-  =  46.3  hrs. 

32  -  20 

These  do  not  check,  because  the  value  of  K  used  above  is 
lower  than  can  be  used.  If  4  were  used  in  place  of  3.3,  the  two 
would  check.  However,  the  previous  value  of  3.3  will  be  used. 
If  now  the  temperature  of  the  brine  is  reduced  to  16°  F.  the 
heat  removed  per  hour  would  be 

20.83  X  (32  -  1  6)  X3-3  =  i  ioo. 


Hours  =  4  hrs. 

I  IOO 

Total  cans  per  ton  per  day  with  15%  allowance 
2000 


24X300 


X44Xi.  15  =  14.1 


From  p.  305  it  is  seen  that  14  cans  are  allowed  per  ton, 
but  16  cans  are  allowed  by  Shipley  (p.  307).  Using  16,  the  total 
number  of  cans  would  be 

Number  of  cans  =  50  X  16  =  800  cans. 

If  this  is  made  16  cans  wide  and  50  cans  long  the  tank  sizes 
will  be 

Length  =  5o[nJ  +  1  +  i±  +  i]  =  62'  6"; 


Width  =  i6[ 

Depth=45"+6"=4'3". 

Problem  13.     Find  the  space  required  for  a  plate  plant  of 
50  tons  capacity,  using  ammonia  at  16°  F. 


PROBLEMS  427 


Volume  of  ice  per  day  =  —        —  =  1  740  cu.f  t. 

Total  length  if  8-ft.  depth  and  i2-in.  thickness  is  used 


If  6  coils  are  used,  giving  12  plates,  the  length  is  given  by 


12 

Using  1  2  -in.  clearance  the  length  of  the  tank  will  be 

i2Xi2"+6Xi2"+6"+6"  =  i9'. 
Tank  size=  19'  X  18^X3'. 

Time    to    freeze  =  —     —=189    hrs.  =  7.9    days  =  8    days 

(P-  3°4). 

Eight  tanks  will  be  required. 
Floor  space  =  43'  X  92'. 

Problem  14.     Find  the  coil  surface  required  for  the  tank 
of  Problem  12. 

Heat  removed  per  pound  of  ice  made  =  200  B.t.u.  (p.  308) 

L    £  'I          50X2000X200          „ 

Heat  from  coil=—  -  =  833,400  B.t.u.  per  hr. 

24 

Assume  10°  difference  between  ammonia  and  brine. 
K=i5  (p.  306). 


Surface  of  coil  =  =  5560  sq.ft. 

Linear  feet  of  i|-in.  pipe  =  5560X2.  301  =  12,800  ft. 
From  p.  307  the  requirement  would  be 

Lin.  ft.  =  250X50  =  12,500. 
If  17  coils  60  ft.  long  are  used  the  coils  must  be  13  pipes  high. 

1      XT      i_       r    •  12,800 

Number  of  pipes  =  —J  —  =12.5. 

This  requires  41  in.  of  height  if  3  centers  are  used. 


428  ELEMENTS  OF  REFRIGERATION 

Problem  15.     Find  the  tons  of  refrigeration  for  plant  of 
Problem  12,  if  30  B.t.u.  are  required  for  cooling. 

„          ,     r  .          .         50  X  2000  X  (200 +30) 

Tons  of  refrigeration  = —  °     =  80. 2 . 

24X60X199.2 

Problem  16.     Find  whether  or  not  ice  storage  will  pay  with 
load  curve  shown  on  p.  309. 

Average  machine  capacity,  150- tons. 

Peak  load  capacity,  325  tons. 

Ice  to  be  stored  with  150  ton  machine: 

May              25X31=  775 

June              65X30=  1950 

July             175X31  =  5425 

August        170X31=  5270 

September  130X30=  3900 

October         55X31=  1705 

Total  I9;°25  tons. 

,,  ,           r.        19,025X2000     ,,  ,, 

Volume  of  ice  =  -^   — =  662,000  cu.ft. 

57-5 

Size  of  house  =  130  X 1 30  X4o  =  676,000  cu.ft. 
Cost  of  building  =  0.06  X 676,000  =  $40,560.00. 

(From  p.  344.) 

Insulation,  two  2"  cork.    0.40X37,700=   15,080.00. 


$55,640.00 
Yearly  cost  on  building: 

Interest 6% 

Taxes  and  Insurance i% 

Depreciation 5% 

Repairs i% 

/  ••    '  -      :'    -  13% 

13%  of  $55,640.00  =  $  7,233.20 
Cost  of  handling  and  holding  =  $0.25X19,025=     4,756.25 

(P-  375-) 

Total  cost  of  storing  ice $11,989.45 


PROBLEMS  429 

Cost  of  extra  apparatus  if  no  storage  is  used: 

175-ton  compressor  and  engine  with  condenser, 
piping,  receiver,  oil  separator $  23,000.00 

BoileJl75X2-5X2°  =  292  Boiler  H.P.Y 

V       3°  / 

including  chimney  piping,  pump  (p.  378) ....  9,000.00 

Cans,  tank  and  coils 19,000.00 

Distilling  apparatus '. 3,800.00 

Erection 9,000.00 

Additional  building  space  400,000  at  10  cts. 

(100X20X20) 40,000.00 

Total  cost $102,800.00 

From  p.  347,  the  cost  per  ton  is  $500.00,  giving 

as  the  probable  cost $  87,500.00 

Amount  assumed  as  cost 95,000.00 

With  8%  depreciation  and  3%  for  repairs  the  fixed  charges 
willbei8%. 

Fixed  cost  per  year=  i8%X95,ooo                  =  $17,100.00 
Additional  labor  cost 1,500.00 


Total $18,600.00 

Saving  by  use  of  storehouse  =  $18,600  —  $i 2,000  =      $6,600.00 

Problem  17.  Find  the  cost  per  ton  of  pumping  water  for 
ice  in  a  raw-water  plant  of  100  tons  capacity  if  the  water  is  200  ft. 
below  surface,  using  anthracite  buckwheat  coal. 

100X2000X1.15       ,.    „ 

Water  per  minute  =  —  — ^  =  160  Ibs. 

24X60 

160X200 

Water  horse-power  =  —          —  =  0.965. 
33>°oo 

(a)  Power  of  steam  end  of  deep-well  pump  =  °'^  **  =  1.29  H.P. 

°-75 
Steam  required  =  1.29X1 20  =I55  lb. 

(P-  35I-) 


430  ELEMENTS  OF  REFRIGERATION 

•n         J  u  I55XICOO  ., 

Pounds  coal  per  hour  =  — —  =  16.1 

12,800X0.75 

Tons  of  coal  for  water  pumping  per  ton  ice  = 


100X2240 
=  0.00172  ton. 

Cost  of  coal  for  pumping  per  ton  of  ice  =  0.00172X13.10 

=  $0.00533. 
Cost  of  attendance  per  ton  of  ice  (50  cts.  per  ton  of  coal) 

=  $0.0008. 
Cost  of  pump  end  equivalent  part  of  boiler,  assumed 

$100.00. 

A.L       erf     .c     j     t.  r    •        $100.00X0.20 

At  20%,  fixed   charges   per    ton   of   ice  =  — 

365X100 

=  $0.00055. 
Total  cost  of  pumping  per  ton  of  ice  =  $0.00668. 


(b)  Power  for  air-lift  pump=  =  2.41  H.P. 

0.40 

Pounds  of  steam  per  hour  =  2.41X35  =84.4  Ibs. 

rr  £  r    •  84.4X1000X24 

Tons  of  coal  per  ton  of  ice  =  — 

12,800X0.75X100X2240 

=  0.00095. 

Cost  of  coal  for  pumping  water  per  ton  of  ice  =  0.00095 
X  $3.  10  =  $0.00244. 

Cost  of  attendance,  =  $0.00048. 

Cost  of  pump  end  equivalent  part  of  boiler,  =  $250. 

~  ,.   .       ,       -      ,     ,  $250X0.20 

Cost  per   ton  of  ice   for   fixed   charges  =  -  ^— 

100X365 

=  $0.00137. 
Total  cost  of  water  pumping  per  ton  of  ice  =  $0.00429. 

Problem  18.  Find  the  steam  and  surface  necessary  to  evap- 
orate 40  tons  of  water  per  24  hours,  with  steam  at  5.3  Ibs.  per 
sq.in.  gauge  pressure  and  of  quality  i.oo. 


PROBLEMS  431 

Temperature  of  steam  at  20  Ibs.  abs  ........  228°  F. 

Temperature  assumed  in  evaporator  .........  193°  F. 

Pressure  in  evaporator,  Ibs.  abs.  ....  ........         9  .96 

Vacuum  in  evaporator  .....................         9.7" 

Heat  content  of  steam  entering  .............  IJ57  •  7 

Heat  content  of  steam  leaving  ..............  H44-3 

Heat  content  of  water  at  193°  F  ............      160.92 

External  surface  of  evaporator,  assumed  .....  250  sq.ft. 


Heat  loss  from  2  in.  of  85%  magnesia  =  2  50  X-^—  [193  —  90] 

T^ 
=  5408  B.t.u.,  using  (i)  p.  302. 

M,(i  157-7  ~  160.92)  =  -          —  [i  144.3  -  160.921  +  5408 


=  3,278,000+5408  =  3,283,408. 


996-7 

4O  X  2000  f  ,      ^ 

— (1144.3-160.9) 

Tube  surface  required  =  -  -  =4205  sq.ft. 

400(228-193) 

This  requires  thirty-two  4-in.  tubes  6  ft.  long,  using  a  drum 
about  5  ft.  in  diameter. 

Problem  19.  Find  the  size  of  filter  to  be  used  for  filtering 
the  raw  water  for  a  loo-ton  plant. 

< 1. 15  =  19.1  gal.  per  min. 
02.5X24X231x00 

Allow  2.5  gal.  per  min,  per  sq.ft.  of  filter  (p..  287). 

Area  of  deck  =  ^^  =  7. 6  sq.ft.  =  1094  sq.in.     Diam.  =38''. 
2-5 

Problem  20.    Find  the  size  of  compressor  to  be  used  for  a 
raw-water  ice  plant  of  100  tons  capacity. 
(a)  Find  Power. 

100  tons  requires   1600  cans  of  3OO-lb.  capacity  each . 
Air  required  =^  (1.8+0.3)  ~ °-7  cu.ft.  per  min.  per  can. 
Total  air  =  0.7X1600  =  1120  cu.ft.  of  free  air  per  min. 


432  ELEMENTS  OF  REFRIGERATION 

Assume  90%  for  volumetric  efficiency  of  a  compressor 
running  at  120  R.P.M. 

Displacement  = =  5.2  cu.ft.  =  oooo  cu.in. 

0.90X240 

Use  20"  X  30".     Displacement  =  9 560  cu.in.     . 

Power  required  =  0.4X1  oo  =  40.0  H.P.  (p.  296). 

Power  required  for  air  compressor  by  calculations  to  com- 
press 1 1 20  cu.ft.  per  minute  to  18  Ibs.  per  sq.in.  by  gauge  will 
be  found  to  be  64  H.P. 

Problem  21.  Find  the  power  to  drive  the  compressor 
required  for  Problem  15,  the  size  of  the  compressor  and  parts, 
the  amount  of  water  for  the  condenser,  and  the  condenser  sur- 
face. Temperature  of  cooling  water  65°  F.  (See  pp.  72, 
et  seq.) 

Temperature  of  evaporation 6°  F. 

Temperature  of  cooling  water  at  inlet.  .  .     65°  F. 

Temperature  of  water  at  point  at  which 

ammonia  reaches  the  saturated  state .  .  80°  F. 

Temperature  of  after-cooled  liquid 7  5  °  F. 

Temperature  of  ammonia  in  saturated 

portion  of  condenser 90°  F. 

Heat  content  of  dry  saturated  ammonia  at 

6°  F : 540.1 

Entropy  of  dry  saturated  ammonia  at6°F.       1.1616 

Specific  volume  of  dry  saturated  ammonia 

at6°F 8.02 

Pressure  at  6°  F 34.60  Ibs.  per  sq.in. 

Pressure  at  90°  F 181 . 80  Ibs.  per  sq.in. 

Heat  content  at  181.8  and  entropy  1.1616.  644.0  B.t.u. 

Heat  content  of  dry  vapor  at  181.8 558.9  B.t.u. 

Heat  content  of  liquid  at  QO°  F 65.3  B.t.u. 

Heat  content  of  liquid  at  75°  F 47 . 8  B.t.u. 

Temperature  of  ammonia  at  end  of  com- 
pression   211°  F. 

Specific  volume  at  end  of  compression. .  .         2.18  cu.ft. 


PEOBLEMS 


433 


Amount  of  ammonia  to  produce  80.2  tons 
80.2X199.2 


Power  to  drive  compressor^  '^         -  54  •  ;  = 

42.42X0.75 


102  H.P. 


The  size  of  the  compressor  is  fixed  after  the  clearance  is 
known.  The  clearance  is  made  small  so  as  to  give  a  large  volu- 
metric efficiency.  The  clearances  of  ^  in.  on  the  upper  end  and 
J  in.  on  the  bottom  end  have  been  used  on  double-acting  cylinders 
and  in  single-acting  cylinders  with  a  safety  head  -gV  in.  and  even 
eV  in.  have  been  used  on  the  upper  end,  while  that  at  the  lower 
end  may  be  anything.  With  small  clearances  the  clearance 
volume  will  amount  to  about  J%. 

As  was  pointed  out  earlier  there  is  no  effect  of  clearance  on 
the  work  done,  except  in  a  slight  degree,  due  to  friction  from 
longer  strokes  with  larger  clearances.  The  effect  on  volumetric 
efficiency  is  quite  marked  and  hence,  the  amount  of  ammonia 
handled  at  a  given  speed  and  with  it  the  amount  of  refrigeration. 
The  York  Mfg.  Co.  has  performed  a  number  of  experiments  on 
their  double-  and  single-acting  compressors  with  various  amounts 
of  clearance  and  has  obtained  the  results  given  in  the  following 
table: 


COMPRESSOR  I.  H.  P.  PER  TON  FOR  SINGLE-ACTING  AND  DOUBLE-ACTING  COM- 
PRESSORS WITH  VARIOUS  CLEARANCES 


Clearance  Volume 

H.P.  at 

H.P.  at 

H.P.  at 

Linear 

in  %  of  Displace- 
ment, 

S  Lbs.  Suction 
Pressure 

15.67  Lbs.  Suction 
Pressure 

25  Lbs.  Suction 
Pressure 

Cle  arance 

S.A. 

D.A. 

S.A. 

D.A. 

S.A. 

D.A. 

S.A. 

D.A. 

fc" 

0.24 

1-75 

1.30 

1.09 

7T-" 

o  42 

2.18 

1.  60 

I    26 

1" 

0.76 

0.85 

1.77 

2-34 

1.32 

1  .62 

1  .10 

1.28 

r 

1.46 

1-55 

i.Si 

2-45 

i-34 

1.64 

1  .11 

1.30 

i" 

2.85 

2-93 

1.82 

2.56 

1.36 

1.72 

I  .12 

1-35 

i" 

5.63 

5-7i 

1.83 

2.89 

1-39 

2.OI 

I-I3 

1-44 

NOTE. — S.  A.     Single-acting  Compressor. 
D.  A.     Double-acting  Compressor. 
Clearance  Volume  includes  indicator  connections,  valve  shut. 


434 


ELEMENTS  OF  KEFRIGERATION 


TONNAGE  PER  24  HOURS  FOR  SINGLE-ACTING  AND  DOUBLE-ACTING  COMPRESSORS 
WITH  VARIOUS  CLEARANCES 


Clearance  Volume 

Tons  at 

Tons  at 

Tons  at 

Linear 

%  of  Displace- 
ment 

5  Lbs.  Suction 
Pressure 

15.67  Lbs.  Suction 
Pressure 

25  Lbs.  Suction 
Pressure 

Clearance 

S.A. 

D.A. 

S.A. 

D.A. 

S.A. 

D.A. 

S.A. 

D.A. 

JL" 

o  24. 

22    7 

38  o 

CQ  A. 

ITf" 

0.42 

IO    2 

-35      O 

47    A. 

r 

0.76 

0.85 

22.6 

17-3 

37-2 

32.1 

50.1 

45-i 

i" 

1  .46 

i-55 

21.0 

16.0 

35-6 

30.0 

49.1 

44-8 

i" 

2.85 

2-93 

19.7 

14-3 

34-4 

28.9 

47.0 

42.3 

i" 

5.63 

5-71 

15-5 

10.6 

29.7 

22.9 

42.6 

36.5 

For  |%  clearance  the  clearance  factor  is 


1+0.005— o.oo5(: 


=o- 


A  34.0 

If  5%  leakage  around  valves  and  piston  is  assumed  the 
volumetric  efficiency  is 

0.95X0.988  =  0.939. 

Displacement  per  min.  =^— ^ —  =  278  cu.ft. 

0-939 

The  piston  speed  used  in  refrigeration  work  varies  from 
•  140  ft.  per  minute  in  compressors  of  5  tons  to  500  ft.  per  minute 
with  compressors  of  300  tons  capacity.  These  give  140  R.  P.  M. 
for  the  small  compressors  and  50  R.  P.  M.  for  the  large  ones. 
Using  2  compressors  with  2  cylinders  each  at  80  R.  P.  M.  the 
displacement  of  one  cylinder  is 

Displacement  = — --  =  0.87  cu.ft.  =  1500  cu.in. 

2  X  2  X  oO 

Sizes  10X19. 
12X13. 

Either  of  the  above  might  be  used  as  the  ratio  of  stroke  to 
diameter  used  in  practice  varies  from  2  to  i  to  i  to  i. 

The  cylinders  are  made  of  close-grain  cast  iron.  They  are 
designed  to  stand  300  per  sq.in.,  using  the  ordinary  formulae  for 


PROBLEMS  435 

cylinder  thickness.  One-quarter  to  f  in.  is  added  for  reboring. 
The  upper  portion  of  the  cylinder  is  jacketed. 

Valves.  The  valves  should  be  as  large  as  possible.  About 
25%  of  the  piston  area  is  sometimes  found  in  valve  area.  The 
velocity  through  the  valves  may  be  used  to  determine  the  valve 
area.  In  this  case  4000  ft.  per  minute  is  used  in  the  suction 
valves  where  the  increase  of  pressure  is  noticeable,  while 
10,000  ft.  per  minute  has  been  used  through  discharge  valves. 
In  any  case  make  the  area  as  large  as  possible.  In  single-acting 
compressors  or  their  equivalent  the  suction  valves  are  prac- 
tically as  large  as  the  piston.  The  discharge  valves  may  be 
single  large  valves  as  in  the  Frick  vertical  or  a  number  of  smaller 
valves  as  in  the  Frick  horizontal  compressor. 

Pipe  Connections.  The  pipe  connections  are  of  such  a  size 
that  the  velocity  is  4000  ft.  per  minute  on  the  suction  side  and 
8000  on  the  discharge. 

Fmc  =--  —  X  144  =  4.7  sq.in.  or  3-in.  extra  heavy  pipe. 


"-X  144  =  0.64  sq.in.  or  i-in.  extra  heavy  pipe. 


s 

2  X  oOOO 

Use  3-in.  and  2-in.  pipes. 

Pistons.  The  ammonia  pistons  are  designed  for  300  Ibs. 
per  sq.in.  They  are  made  deep.  The  depth  is  about  equal  to 
the  diameter  or  f  the  diameter  of  the  piston.  Some  makers 
use  three  piston  rings,  ground  to  fit  the  ring  groove,  while  others 
use  four  or  five  rings.  The  usual  design  of  rings  is  made.  The 
pistons  are  made  of  cast  iron  or  steel.  They  are  designed  as  flat 
plates  supported  by  a  series  of  beams.  Empirical  constants  are 
found  in  handbooks  of  machine  design. 

Piston  Rod.  The  piston  rod  should  be  made  of  high-grade 
alloy  steel  and  a  factor  of  safety  of  10  should  be  used.  The  rod 
is  attached  to  the  piston  by  a  thread,  using  the  piston  as  a  nut 
or  using  a  separate  nut.  The  section  at  the  root  of  the  thread 
should  be  designed  for  tension.  The  main  body  of  the  rod  is 
designed  as  a  column. 


436  ELEMENTS  OF  REFRIGERATION 

Condenser.    Heat  removed  in  superheater  portion  per  pound  of 
ammonia  =  644.0  —  558.9  =  85.1  B.t.u. 

Heat  removed  in  saturated  portion  per  pound  of  ammonia 

=  558.9-65.3=493.6  B.t.u. 
Heat  removed  in  after  cooler  per  pound  of  ammonia  =  65.  3 

-47.8  =  17.5  B.t.u. 

Amount  of  cooling  water  per  minute 


48.05-33.08 

=  17.75  cu.ft.  per  min. 
=  132.5  gal.  per  min. 
48.05  =q'  at  80  for  water; 
33.08  =  2'  at  65  for  water. 

Temperature  of  water  at  end  of  superheat  is  given  by 


M« 
9o=48.05+3^5± 

=  48.05  +  2.5=50.55. 
/  =  82.5. 

Temperature  of  water  at  end  of  aftercooler  and  entrance  to 
saturated  portion  is  given  by 


Mw 


mo 

=  33.08+0.51=33.59; 
'  =  65.5- 
Temperature  Differences: 

At  inlet  aftercooler 75  —  65     =  10 

At  outlet  aftercooler 90  —  65.5  =24.5 

At  inlet  superheater 90  —  80     =  10 

At  outlet  superheater 211  —  82.5  =  128.5 


PROBLEMS  437 

Mean  Temperature  Differences: 

For  aftercooler  AJ  =    24'5~IQ   =  16.2  ; 


For  saturated  portion  AT      =    24'^  —  —  =  16.2  ; 


For  superheated  portion  Ar  =  —  *  —  '^     *°   =46.3. 

,         I2O.S 

2.3  log  - 

IO 

If  the  water  is  forced  through  the  double-pipe  condenser 
at  5  ft.  per  second,  the  value  of  K  would  be  275,  from  Fig.  94. 
From  formula  (18)  the  value  is  291  and  by  (20)  it  is  220  with 
2-in.  and  3-in.  pipes.  On  Fig.  188  the  value  of  K  is  100.  The 
value  of  200  will  be  used  in  the  problem. 


16.2X200 

For  the  aftercooler  400  will  be  used  for  K  (p.  187). 

=  60X32.5X17.5  ft 

16.2X400 

For  the  superheated  portion  (22)  p.  188  gives  K  =  $o. 

60X32.5X85.1  ^ 

Fm»  =  --  r^  —  *-  =  122.0  sq.ft. 
46.3X30 

Total  surface  with  |  increase  as  safety  factor  =  566  sq.ft. 

The  ordinary  rules  call  for  from  8  to  18  sq.ft.  per  ton.  This 
would  give  640  to  1440  sq.ft.  The  difference  between  556  and 
640  is  due  to  temperature  difference.  With  water  at  tempera- 
tures taken  556  sq.ft.  is  sufficient. 

If  the  condenser  is  made  up  of  2-in.  and  3-in.  pipes  and  no 
allowance  is  made  for  cooling  from  the  outside,  the  total  length 
will  be 

Total  length  =  566  X  i  .608  =  910  ft. 

Number  of  stands  of  12  pipes,  20  ft.  long  =  11$  =4. 


438  ELEMENTS  OF  KEFRIGERATION 

In  Block  condensers  9  lin.ft.  per  ton  is  allowed.  This 
requires  about  720  linear  feet.  Shipley  uses  8  ft.  per  ton  in  his 
improved  condenser.  Ordinarily  with  temperatures  occurring 
in  practice  25  Im.ft.  per  ton  may  be  allowed  in  double-pipe  con- 
densers of  2-in.  and  3-in.  pipes.  In  the  problem  just  worked  out 
about  ii  lin.ft.  per  ton  is  used.  This  is  due  to  the  velocity  of 
the  water  and  the  assumed  temperatures. 

Problem  22.  If  one-third  of  the  refrigeration  of  Problem  21 
is  possible  at  20°  F.  in  place  of  6°  F.,  find  the  size  of  compressor 
and  power  required  for  this  if  a  Voorhees  multiple  effect  in- 
stallation is  used. 

Refrigeration  at    6°  F  ................   53.5  tons 

Refrigeration  at  20°  F  ................   26.7  tons 

Dry  compression  or  x  =  i  at  discharge  from  coils: 

i"  §*  ......................  540.  i  B.t.u. 

Ao°  .......  ..............  543.  7  B.t.u. 

^750  ..............  ........  47  .  8  B.t.u. 

V"Q  ......................  8.02  cu.ft. 

z/r2o  .  •  ...................  5  .  92  cu.ft. 

PQ*  .....  •  ••  •  ...........  ...  34-6 

#2o«  ......................  47-75 

53-  5  X  199.  2     21.7 


. 

540.1-47.8 

j,,  26.7X199.2 

M  2  ......................  :     =  10.8 

543.7-47.8 

Volume  of  cylinder  for  21.7  Ibs.  at  6°  =  21.  7  X8.O2  =  174  cu.ft. 

Volume  of  i  Ib.  after  adiabatic  compression  from  34.6  to  47.75, 
6.32  cu.ft. 

Volume  of  cylinder  to  care  for  addition  at  20°  =  21.  7X6.32 
+  10.8X5.92  =  201  cu.ft. 

If  the  compressor  is  built  of  174  cu.ft.  capacity,  the  10.8  Ibs. 
of  ammonia  will  not  be  drawn  in  at  47.75  Iks.  pressure  and  the 
refrigeration  cannot  be  done  while  a  displacement  of  201  cu.ft. 


PROBLEMS  439 

per  minute  would  lower  the  back  pressure  in  the  lower  system 
to  29.3  Ibs.  per  sq.in.  and  more  work  would  have  to  be  done. 

Specific  volume  =  -  =  9.28  ; 
21.7 

Pressure  =  29.3. 

This  cannot  be  changed  if  it  is  necessary  to  divide  refrigera- 
tion, as  stated. 

Condition  after  mixing  is  given  from  specific  volume. 

Specific  volume  =  f  f  J  =  6.  18  ; 
Pressure  =47.75  Ibs.  per  sq.in.; 

Temperature      =35°  F.  (superheated  15°); 
Heat  content     =553.1; 
Entropy  =1.153. 

After  compression  to  181.8  the  conditions  are: 

Entropy         =1.153; 
Heat  content  =  638.0. 

Work  of  compression  =  (Mi  +  M  2)  fe  —  ii)+A(p\—  po)v 
=  32-  5[^-553-i]+TT8  i44(47-75-29-3)20i 
=  3453  B.t.u.  per  min. 


I.H.P.  of  motor  =  -        --  =  108.5. 
42.42X0.75 

The  power  required  in  Problem  21  was  102,  so  that  this  is  not 
of  any  advantage  on  account  of  the  lower  back  pressure.  If, 
however,  the  load  could  be  divided  so  that  a  smaller  tonnage 
would  be  taken,  at  the  higher  pressure  then  there  might  be  some 
economy.  If  18  tons  are  used  at  the  higher  pressure  the  results 
are  better. 

,,      62.2X199.2 

Mi=—  —  =  25.1  Ibs.; 

492.3 

-,,      18X199.2 

M2  =  —         -  =  7.  2  Ibs. 

495-9 


440 


ELEMENTS  OF  REFRIGERATION 


Volume  of  cylinder  for  low  pressure  =  25.1  X8.O2  =  201. 
Volume    of    cylinder    for    high    pressure  =  2 5. 1X6.3 2 +  7. 2 

X5-92=20I.2. 

This  checks  and  the  system  will  operate. 

*7OT 

Specific  volume  of  mixture  at  47.75  Ibs.  = =  6.21. 

324 

Temperature  =  35°  F. 
Heat  content  =  553.0; 
Entropy  =1.153- 

After  compression  to  181.8  at  entropy  1.153  the  heat  content 
is  638. 


I.H.P.  = 


[32-3(638- 553) +TT¥  144(47.75-34.6)201] 


42.42XO.75 
=  IOO.2. 

This  means  a  saving  of  2%  over  the  simple  arrangement. 
With  other  conditions  this  saving  may  be  greater. 

Problem  23.  Find  the  quantity  of  water  at  60°  F.  which 
gives  the  most  economic  results  if  water  for  condensing  is  raised 
100  feet  from  a  stream.  Use  data  in  Chapter  IX  to  fix  costs. 
Assume  temperature  in  coils  to  be  5°  F. 

(a)  Find  cost  of  producing  i  ton  of  refrigeration  if  tempera- 
ture of  condensation  has  different  values  by  methods  below. 


DATA  COMPUTED  FOR  DIFFERENT  QUANTITIES  OF  WATER 


/  of  condensation  

70° 

75° 

80° 

85° 

90° 

95° 

105° 

p  of  condensation  

129.2 

141.  1 

153-9 

167.4 

181.8 

197-3 

231.2 

i    1637 

i  at  end  of  comp  
i  of  liquid  at  68°  F  
t  of  water. 

621.3 
39-9 
65°  F. 

627.1 
68°  F. 

633.5 
70°  F. 

639.6 
75°  F. 

645.2 
80°  F. 

65L9 
85°  F. 

666.0 
95°  F. 

I.H.P  
Gallons  per  minute  
I.H.P.  pump  
Steam  per  hour  for  engine  .  . 
Steam  per  hour  for  pump.  .  . 
Total  steam  per  hour  
Cost  of  coal  and  labor  in  cts  . 
Fixed  charges  on  engine  .... 
Fixed  charges  on  pump  .  .  . 
Fixed  charges  on  condenser  . 

1.02 

5.56 

o.  187 
24.5 
28 

S3.  5 
1.07 
0.038 
o.  105 
0.014 

I  .  10 

3-52 
0.118 
26.4 
17.8 
44-2 
0.88 
0.041 
0.066 
0.009 

1.18 
2.83 
0.096 
28.3 
14.4 
42.7 
0.85 
0.044 
0.054 
0.007 

1.25 
I.9I 
0.064 
30.0 

9'f 
39.6 

0.79 
0.046 
0.036 
0.006 

1.32 
1.44 
0.049 
31-5 
7.8 
39-3 
0.79 
0.050 
0.027 
0.005 

1.41 
1.07 
0.036 
33.8 
5-4 
39.2 
0.78 
0.052 
0.020 
O.O05 

1.59 
0.85 
0.029 
38.0 
4-3 
42.3 
0.85 
0.059 
0.016 
0.005 

Total  in  cts  per  ton  per  hr.  . 

1.227 

0.989 

0.955 

0.878 

0.872 

0.857 

0.930 

PROBLEMS  441 

The  method  of  computing  is  given  as  follows: 

j|f  =  -  E99^  -  =  0.308  Ib.  per  min. 

539-9-39-9 

I.H.P.  _ 


42.42X0.75 
Gal  per  min. 


(65-60)62.4X231 


...  .. 

1728X33,000X0.75 

Steam  consumption  of  engine  on  compressor,  24  Ibs.  per 
I.H.P.  hr. 

Steam  consumption  of  pump,  150  Ibs  per  I.H.P.  hr. 

Steam  per  hr.  =  24  X  1.02  =  24.5. 

Steam  per  Ar.  =  150X0.187  =  28. 

Cost  of  buckwheat  coal,  $3.25  per  ton.  Cost  of  firing,  40  cts. 
per  ton.  Efficiency  of  boiler,  65%.  Temperature  of  feed, 
200°  F.,  pressure  of  steam  125  Ibs.  abs. 

Cost  of  coal  per  1000  Ibs.  of  dry  steam 

_  iooo(i—q0)  Xcost  per  ton 
~  Heat  per  Ib.Xeff.X  2240  ' 

_iooo[ii92.o-  167.951X365  =  2Q  ctg> 
12,800X0.65X2240 

Cost  of  coal  and  labor  =  ^^  X  20  =  i  .07  cts. 
1000 

Cost  of  fixed  charges  on  compressor  engine  of  TOO  H.P.  size 
based  on  1  5%  allowance  and  8000  hours  of  use 

.feo-ooXi.oaXo.is  8  cts. 

8000 

There  is  no  allowance  for  fixed  charges  on  compressor,  as  com- 
pressor size  is  the  same  in  all  of  these  cases. 


442 


ELEMENTS  OF  REFRIGERATION 


„.      ,    ,  $300.00X0.15X0.187 

Fixed  charges  on  pump=-^—   — - — -  =  .105  cts. 

oooo 


Condenser  surface 


_  0.398(^2—35)  X6o 
100  X  A/ 


100X7.5 

Cost  of  condenser  at  40  cts.  per  sq.ft  and  15%  for  depreciation, 

18.6X40X0.15 

taxes,  etc.,  and  8000  hours  =  -  ~       —  -  =0.014. 

8000 

From  the  total  of  cost  it  is  seen  that  1.07  gallons  per  minute 
is  the  most  economical  rate.  If  now  instead  of  having  water  free 
from  a  stream  it  must  be  purchased  at  3  cents  per  1000  gallons, 
the  sums  above  are  increased  giving  the  following  table: 


Gallons  per  minute 

r    r6 

"?    <2 

2    83 

i  .91 

I  .44 

I  .07 

0.85 

Cost  for  water  free  

I  .  227 

o  080 

O.O^ 

0.878 

0.872 

0.857 

0.930 

Cost  of  water  

I  .OOO 

O.632 

0.510 

0.344 

o.  259 

O.I93 

O.I53 

Total  cost  with  water  

2.227 

I.52I 

1.465 

I  .222 

I.I3I 

1.050 

1.083 

Cost  of  water  =  ^-  X  60  X  3  =  i  .00. 


1000 


The  result  is  the  same  as  before,  although,  if  these  results  are 
plotted  into  a  curve,  the  most  economical  rate  will  be  found 
higher.  At  6  cents  per  1000  gallons  the  total  cost  at  1.07 
gallons  would  be  1.243  c^s-  against  1.236  at  0.85  gallon;  show- 
ing that  at  this  cost  for  water,  the  cost  of  water  would  offset 
the  additional  cost  of  power. 

Problem  24.  Find  the  size  of  cooling  tower  to  cool  the 
water  required  in  Problem  22  for  80.2  tons  of  refrigeration  with 
102  H.P.  and  a  steam  consumption  of  25  Ibs.  of  steam  per 
horse-power  hour.  The  water  is  to  be  cooled  from  95  to  60°  F. 
in  70°  weather,  with  the  wet  bulb  temperature  of  60°  F. 

Amount  of  water  from  ammonia  condenser  =  1.07X80. 2 
=  85.8  gallons  per  min. 


PROBLEMS  443 

Amount  of  water  from  steam  condenser 

^102X25X1000^728  Q 

"  35X60X62.4  '    231 

Total  water  per  minute  to  tower  =  228.8  gallons  =  1910  Ibs. 

Relative  humidity  from  Fig.  92  ..........  0.49 

Relative  humidity  at  discharge  ..........  i  .  oo 

Temperature  of  air  at  entrance  ..........  70°  F. 

Temperature  of  air  at  discharge  .........  95°  F. 

Temperature  of  water  at  entrance.  ......  95°  F. 

Temperature  of  water  at  discharge.  .  .....  60°  F. 

Barometric  pressure  ....................  14.7 

Assume  volume  of  air  at  entrance  .........     i  cu.ft. 

Weight  of  moisture  at  entrance  =  0.001153  X  0.49  =  0.000564. 
Volume  of  air  at  discharge 

_  144(14.7-0.49X0.3628)  ^        (460+95)       _r 
460+70  (14.7-0.815)144 


Moisture  in  air  /em>wg  =  1.095X0.002474  =  0.002  71  Ib. 

Moisture  absorbed  =  0.00271—  0.00056=0.00215  Ib. 

Assume  water  entering  when  i  cu.ft.  of  air  enters  is  equal 


to  m". 


Energy  Entering: 

With  water,  w"X63.oi  =63.01  m"  \ 

VIT-^L    •     i-4     144(14.7—0.40X0.3628) 
With  air,  --X-          '  —^—  =  9.42; 

0.4  778 

With  moisture,  o.ooo565[io8i.5  +  (7o  —  50)0.6]=  0.62. 


Energy  Leaving:     . 
With  water,  (m"  -0.002  15)  (28.08)  =  28.o8w"  -0.06. 

With  air,  14  x  144(14.7-0.815)1.095  =    86. 
0.4  778 


444  ELEMENTS  OF  REFRIGERATION 

With  moisture,  0.00271X1102.3  =  2.99. 
Equating: 
63.01  m"+<).  42  +0.62  =  28.08  m"  —  0.06+9.86  +  2.99. 

i 

-77  =  12.7 
m" 

12.7  cu.ft.  of  air  must  be  taken  in  per  Ib.  of  water  entering. 
12.7X0.00215=0.0273  Ib.  moisture  absorbed   per   pound 

entering. 

Total  air  per  minute  =  12.  7X1910  =  24,200  cu.ft.  per  min. 
With  a  velocity  of  700  ft.  per  second,  this  would  require  a  cross- 
sectional  area  of 

=  35  sq.ft.     (S'X7'.)  .       • 

An  atmospheric  tower  would  require 

228X1  =  228  sq.ft.     (15X15'.) 
A  cooling  pond  for  this  plant  would  contain 

228X70  =  15,960  sq.ft.     (160X100'.) 
The  basin  for  spray  nozzles  would  contain 

228X2  =  556  sq.ft. 

There  would  be  a  set  of  four  2^-in.  nozzles,  as  each  would 
care  for  about  70  gallons.  Two  sets  would  be  required  for  35° 
cooling. 

Problem  25.     Find  the  amount  of  refrigeration,  surfaces 
for  brine  cooler,  condenser  and  bunker,  and  fan  size  for  the 
air  conditioner  for  a  450-ton  furnace  (450  tons  per  day),  when 
the  air  is  at  90°  F.  and  the  wet  bulb  shows  85°  F. 
(a)  Refrigeration: 

Relative  humidity  (Fig.  93)  ........  0.82 

Partial  vapor  pressure  =  0.82  X.  698.  .  0.57 

Temperature  of  air  leaving  .........  34°  F. 

Assume  air  required  per  minute  .....  40,000  cu.ft. 

Volume  of  air  leaving  =  40,000  X  I44/14'7  ~  °;57) 

(460+90) 

(460+34) 


144(14.7-0.0961) 


PROBLEMS  445 

TIT  •   T.^      r      •  •  4O,OOO  X  144  X  (14.  13) 

Weight  of  air  entermg=—  -^  =  2700  Ibs. 

53-35X550 

Weight    of    moisture    entering  =  40,000X0.82X0.002  13  7 

=  70  Ibs. 

Weight  of  moisture  leaving  =  34,900X0.000327  =  11.4  Ibs. 
Water  condensed  per  minute  =  58.6  Ibs. 

„,  ,  ,      58.6X60X24X1728 

Water  condensed  per  day  -  -  —  -  —  =  10.100  gal. 

62.4X231 

Entering: 

Energy  in  air  at  entrance  above  32°  F. 

=  0.24X2790(90-32)=  38,900 
Energy  in  moisture  at  entrance  above  32°  F. 

=  70  X  [1097.3  +  (90  -34)0.6]=   77,063 

Total  ...............................  115.963 

Leaving: 

Energy  in  air  at  exit  above  32°  F. 

=  0.24X2790(34-32=      1335 
Energy  in  moisture  at  exit  above  32°  F. 

=  11.4X1074=   12,250 
Energy  in  water  at  exit  above  32°  F.  =  58.6X2.01  =        118 

Total  ................................  13.703 

Heat  removed,  115,963  —  13,703  =  102,260  B.t.u.  per  min 

r~         r     r  -       4-      f  i          102,260 

Tons  of  refrigeration  for  air  alone  =  —        —  =  513  tons. 

199.2 

(b)  Surfaces  required: 

Air  temperature  entering,  90°  F.; 
Air  temperature  leaving,  34°  F.; 
Brine  temperature  entering,  24°  F.; 
Brine  temperature  leaving,  39°  F. 


Mean  Ar  =       ---       =  _ 

log.fi  2.12 


446  ELEMENTS  OF  REFRIGERATION 

Assume  velocity  of  air  900  ft.  per  min. 


,-,     102,260X60  ,, 

F  =  —  —  =  38,200  sq.ft. 

19.4X8.5 

Use  2-in.  pipes,  20  ft.  long.     Pipe  surface  =  20  X — 7-—  =  12.45. 


i. 


Number  of  pipes = —    —  =  3060  pipes. 
12.45 

If  sections  are  made  up  of  sections  25  pipes  high  and  3  sec- 
tions above  each  other,  the  number  of  rows  will  be 


Rows= 


3X25 

-       .      40,000  •-, 

Area  for  air  =  —      —  =  44.4  sq.ft. 
900 


Width  between  rows  of  tube  =  -—  Xi2  =0.65". 

41X20 


Total  length=---     =  I^  4y/. 

If  three  division  walls  or  plates  are  placed  in  bunker,  this 
may  be  made  13  ft.  o  in.  long. 

The  width  of  bunker  will  be  30  ft.  to  allow  5  ft.  at  each  end. 
The  height  will  be 

75(4"  centers)  +3  X6"  =  26'  6". 

The  heat  loss  from  bunker  with  3-in.  cork  insulation  on  i2-in. 
brick  will  be 

2340X  [90-2^41  Xo.o7=458o  B.t.u. 
(#  =  0.07,  p.  211). 

Tonnage  in  radiation  =  —  —  =  23  tons. 
199.2 


Tonnage  in  6/^  =  513  +  23  =  536  tons. 


PROBLEMS  447 


Brine  coils: 

Assume  ammonia  at  9°. 


°  0.692 

Assume  velocity  of  5  ft.  per  sec.     From  Fig.  95,  #  =  137. 

„     536X199.2X60  r, 

F  =  —  --  ^—      —  =  2145  sq.ft. 
137X21.7 

Using  i|-in.  pipe  20  ft.  long  and  10  high  for  one  coil,  the 
surface  per  coil  will  be 

200X—  =  99-5  sq-ft-> 

2.OI 


Number  of  coils          =  22  coils. 
99-5 

With  no  circulation  in  pipe  the  rules  on  Fig.  189  would 
require  29,315  sq.ft.,  but  in  this  rule  the  temperature  difference 
is  small. 

Suppose  brine  tank  is  20X11X8  ft.  The  surface  will  be 
936  sq.ft.  and  the  heat  loss  will  be 

936X0.07X^90-^^]  =3800. 


Tons  of  Radiation  =  -~  =  19  tons. 
199.2 


Total  /0?wage  =  536H-i9  =  555  tons. 

Condenser  surj  'ace  =  5  55X40  =  22  ,200  sq.ft.    If  the  ammonia 
were  in  condition  of  Problem  21,  the  surface  would  be 

555X7=3885  sq.ft. 

This  would  require  12  stands  of  2-  and  3  -in.  double  pipe  con- 
densers, each  10  high  and  20  ft.  long. 

3885 

0       y  =12.1. 


20XIOXI.608 


448  ELEMENTS  OF  REFRIGERATION 

(d)  Fan  Size.    Pressure  in  actual  plants  (p.  321)  =  1.2  oz. 
Use  Buffalo  conoidal  type. 
Pressure  1.2  oz. 

Equivalent  volume  at  2  oz.  =  4o,ooo\/—  =  51  ,600   cu.f  t.   per 

min. 

Use  No.  130  fan; 


2 

—  =  226; 


Actual  quantity  =  64,700.   —  =  50,000; 


+J  y" 

2      64,700 

The  fan  is  larger  than  required,  but  it  is  the  nearest  that  can 
be  obtained  from  table.  The  fan  would  be  129  in.  high,  6  ft. 
6  in.  wide  and  109^  in.  long. 

Problem  26.  Find  the  amount  of  refrigeration  and  power 
to  operate  a  water-cooling  system  to  supply  1000  men  in  a  plant 
when  the  length  of  the  circuit  is  5100  ft.  arranged  in  parallel 
circuits  1700  feet  long  with  20  elbows.  The  water  is  75°  in 
90°  weather. 

Men  on  i  shift 600 

Quantity  of  water 600 X|  =  150  gals,  per  hr. 

=  50  gals,  per  hr.  in  circuit 

=  412  Ibs. 
Number  of  fountains -63°or  =  20 

Length  of  pipe  at  each  fountain,  20  ft. 

Total  length  of  i  circuit,  i7oo+-236-X2o=i84O  ft. 

Elbows  in  i  circuit  =  4X7 +  20  =  48. 

(a)  Refrigeration:  ~, 

Mean  temperature  of  water,  50°  F.; 

Drop  in  line  temperature,  5° — 52.5  to  47.5°  F, 


PROBLEMS  449 

Using  ice  water  covering  and  assuming  i|-in.  pipe,  the  heat 
loss  is 

(2  =  1840X0.23(90-  50)  =  16,900. 
Weight  of  water  to  care  for  radiation  with  5°  fall 

Ibs.  perhr. 


Area  required  to  give  3-ft.  velocity  (30),  p.  335. 


7^  =  0.00562=0.81  sq.in. 
Use  ij-in.  pipe. 
For  i^-in.  pipe 

Velocity  =        37Q2Xl44     -  =  1.2  ft.  per  sec. 
3600X62.4X2.036 

Total  refrigeration  in  pipe  and  water 

=  i6,9boX3  +  i236[75-5o]  =  6>8 
199.2X60 

Loss  in  two  storage  tanks  of  6  ft.  diameter,  10  ft.  high 
=  220X0.07X40  =  617  B.t.u.  per  hr.  =  0.05  ton. 
Total  tonnage  =  6.  88  tons. 

(b)  Power  required: 


Head  loss  '  ^+48X0.2  X^l^  =  13.8  ft. 

M      *  1-5    64.3 


I2  12 


33,000  X  60  X.  60 
UsejH.P. 

Problem  27.     Using  data  from  test  of  Feb.  5,  1908  (p.  400), 
reduce  refrigerating  effect. 
(a)  From  brine: 

Weight  of  brine  per  revolution  of  pump  ...   41  .  15  Ibs. 
Revolutions  of  brine  pump  in  15  min  ......  419 

Weight  of  brine  per  minute,  4IQX4I-I5  = 


450  ELEMENTS  OF  REFRIGERATION 

Temperature  of  brine  at  inlet  to  cooler  ......   25.n°F. 

Temperature  of  brine  at  outlet  from  cooler.   14.81°    Fe 
Specific  heat  of  brine  ....................     0.678 

Heat  removed  per  minute 

=  ii5oX  (25.1  1-  14.81)  Xo.6y8  =  8049. 

Tons  of  refrigeration  =   °49  =  40.  2  . 
199.2 

I-H.P  ..............  .....:  .............  55.83 

I.H.P.  per  ton  ...................  55^3  =  I>39 

40.2 

(6)  From  ammonia: 

Mean  discharge  temperature  ..........  146.4 

Discharge  pressure  by  gauge  ..........  185  .  06 

Barometer  ..........................  15.01 

Absolute  pressure  ....................  200  .  07 

Temperature  of  saturation  ____  ,  .......  95.  9 

Heat  content  at  185.06  Ib.  and  146.4°  F.  595.9 

Temperature  at  expansion  valve  ........  58.91°  F. 

Heat  content  of  liquid  at  58.91°  F  .....  29.8 

Temperature  in  suction  ...............  17  .  80 

Pressure  of  suction  .............   20.45 

Barometer  ....................   15  .  01 

Absolute  pressure  ....................     35  .46 

Temperature  of  saturation  ............    6.5°  F. 

Heat  content  at  35.46  Ibs.  and  17.8°  F.  .  .    547 

Ammonia  per  minute  2^  '   =15.8  Ibs. 
Refrigeration  =  15.8(547  -  29.8]  =  8180. 


Tons  of  refrigeration.  ---  =41.2. 
199.2 


PROBLEMS  451 

This  is  slightly  greater  than  the  brine  result. 

Cooling  =  15.8(595.9 -29.8)  =8960  B.t.u.  per  min. 

Problem  28.     Check  data  from  test  of  Westinghouse-Leblanc 
machine. 

Refrigeration  =  ^^Xo.833X  (18.40- 15.00)  =935-8. 
oo 

Tons  of  refrigeration, 935'   =4.69. 
199.2 


INDEX 


A 

Absorber 32,  137 

,  tubular ,.  . . 37 

Absorption  machine 31,  79 

system 49 

Accumulator 279 

Adiabatic,  construction  of 114 

After  cooling .  .  ......  . .  ...  ........ 69 

Air 105 

blower ...... .... 295 

circulation 245 

compressors,  cost  of 351 

cooling 318 

of  churches,  hotels,  auditoriums •.•-.-•. 322 

drying 319 

drying  design '. 444 

for  cooling  tower •  •  •  • I  ?6 

leakage,  heat  of 213 

lift  pump 298 

machine  advantage 21 

operation . . 25 

work  of  compression ,•  •  •  • 2O 

pump 283 

quantity ... . .   248,  254 

refrigerating  machines 18 

required  for  raw  water  ice 295 

required  for  room • 420 

supply  header 295 

system  closed 19 

open 20 

velocity 248 

Allen 24 

Allen  dense  air  machine 19 

Ammonia  compressors,  cost  of 351 

evaporated,  in  coil • 420 

main,  size  of 425 

required 257 

Amount  of  refrigeration  for  ice  making 310 

Analyzer , , , , , , , , , , , , , , , ,  33 

453 


454  INDEX 

PAGE 

Apples 227 

Applications  of  refrigeration 312 

Aqua  ammonia 31 

,  partial  pressure 80 

,  specific  heat 83 

,  specific  gravity 83 

,  temperature  of  boiling 80 

Arctic  machine 125,  1 26 

Audiffern-Singrun,  machine 131 

Auditorium  air  cooling 322 

Automatic  refrigeration 263 

Automobiles,  use  of 311 

B 

Bananas -.-.. 229 

Baudelot  cooler 314 

Beal 297 

Bell-Coleman 21 

Belting,  cost  of •. 352 

Berthelot 81 

Bertsch T6; 

Binary  refrigeration 169 

Blast  furnace  application ...    318 

Bohn  ice  box 13 

Boilers,  cost  of,  dimensions  of .....:.-...  348,  363,  365 

Boiling-point 2 

Boyle  Union 142 

Branch  tees 145 

Brewery 241 ,  314 

,  refrigeration  for 317 

Brine 258 

,  amount  of 2  so 

cooler 160,  163,  164,  306 

,  forcing ' 259 

freezing  tank 273 

,  kind  of 2.59 

pipe  and  pump,  size 423 

,  specific  heat 258 

system 27  245 

tank .  34 

tank  coil 259 

velocity  determination 420 

Buildings,  cost  of 343 

Bunker 247 

piping 256 

room 323 

surface,  determination  of 421 


INDEX  455 

C 

PAGE 

Cabbages 229 

Candling 220 

Candy 312 

Cans,  cost  of , 357 

Can  filler 274 

,  ice 289 

,  number  of 305 

required 426 

surface 310 

system 269 

Car,  precooling 264 

refrigerated  data 381 

refrigerator , 13 

Carbondale  machine 36 

Carbon  dioxide  machine 31,  105,  128 

properties 390,  391,  392 

Carpentering,  cost  of 344 

Carre 37 

Carre"  Machines 4 

Carrier 51 

Carrier's  chart 175 

Celery 229 

Cement  wall 201 

Central  refrigerating  plant 260 

station  load 262 

Characteristic  equation , 62,  64 

Cheese 223 

Chemical  work 337 

Chocolate,  specific  heat 313 

Church  air  cooling 322 

Cleanliness  of  plants 303 

Clearance 433 

effect 44,  71,  433 

factor 46 

Clothing 229 

Closed  air  system 19 

Coefficient  for  brine  pipes 306 

of  transmission  of  pipes 255 

Coil,  cooling 18 

,  cost  of 352,  353 

,  data  for 352,  353 

surface 310 

,  amount  of 254 

,  required 427 

,  testing 123,  124 

Coke  filter 300 


456  INDEX 

PAGE 

Cold  storage 217 

,  average  length  of  time 219 

for  brewery 241 

for  florists 231 

for  hotels 238 

for  markets 232 

for  packing  houses 239 

for  ships 240 

heat  loss 243 

laws 217 

products,  value  of. 217 

with  ice 241 

warehouses 5 

Cole.  I.  &  W 26 

Comparison  of  thermometers 395 

Complete  absorption,  heat  of 81 

dilution,  heat  of 81 

Compressed  air  machines 4 

Compression,  dry 68 

,  machines 4 

refrigerating  machine 26 

,  wet 68 

Compressor  air,  size  required 431 

,  cost  of 351 

,  ammonia,  cost  of 351 

,  size  required 432 

,  arctic 125 

,  De  la  Vergne 29,  116,  118 

,  dimensions  of 358,  360,  361 

,  exhausting 125 

,  Frick 28,  122 

,  power  required 432 

,  single  acting 27 

,  York no 

,  aqua  ammonia 31 

Condenser 31,  32,  149 

Block,  cost  of 352,  353 

,  data  for '.. 352,  353 

,  De  La  Vergne 154 

,  design ....... 436 

,  double  pipe 37 

,  exhausting , .  •  •  • 1 23 

,  flanged 152 

,  Philadelphia 15? 

,  oval  flask  steam. . . . — 165 

,  screwed .... ...  •  .......  •  ••...-•  ...... •  •  T53 

,  Shipley , , . .............158 


INDEX  457 

PAGE 

Condenser,  submerged 155 

,  supports 159 

,  surface  steam 165 

,  welded 151 

Conduction 182,  183 

Conduits 261 

Congealer 233 

Constant  quality 58 

vapor  weight  line 58 

volume  line 59 

of  transmission 187 

Construction  warehouses 231 

Cool  brine  system 5 

Cooler  for  sweet  water > 241 

Cooling 46 

,  by  evaporation i 

,  by  solution ~-     t 

,  by  ice .•     3 

,  determination  of , 399 

,  drinking  water 331 

method  of 244 

pond 172 

pond  design 178 

tower 167,  169 

tower  design v 1 76,  442 

tower  test 406 

water 374 

Cool  water  coil 32 

Cooper  system  of  refrigeration 18 

Cork,  best  thickness 407 

board 201 

covering 336 

loss. 334 

Correction  for  hydrometer 395 

of  thermometer'  readings 397 

Cost  of  air  compressors 351 

ammonia  compressors 351 

belting 352,  353 

fan  blowers 352 

boilers 348 

buildings 343 

cans 357 

carpentering 344 

coils 352,  353 

condensers 352,  353 

distilling  apparatus , 357 

electric  generator 350 


458  INDEX 

PAGE 

Cost  of  electric  motors 350 

engines 349 

excavations 340 

floors 345 

gas  engines 350 

ice,  natural 384 

,  manufactured 384 

storage 309 

insulation 345,  346 

land 343 

lumber "..... 344 

machinery 347 

masonry 344 

millwork 345,  395 

miscellaneous  apparatus 357 

operating 376,  377,  378,  379 

partitions 345 

painting 345 

plumbing 345 

pipe  and  fittings 354 

pipe  coverings 346 

pipe  for  storage 357 

plant,  initial 376,  377,  37$,  379 

plumbing,  initial 345 

producers 348 

pumps 351 

receiver 353 

roadway 345 

roofing 345 

separators 353 

space 409 

storage 215,  375 

supplies 357,  374 

switchboard 35° 

water : 374 

Counter  current  flow 47 

Curves,  construction  of. .  . 115 

Cream 225 

Creamery  refrigerators 339 

Crosses 145 

Curve  of  ice  consumption 308 

Cushionhead • 109 

Cycle  diagram 66 

Cylinders 116,  120,  122,  434 

Cylinder  expansion .. . 19 

head 29 

operation  of 123 


INDEX  459 


Dairy  refrigeration 339 

Data  for  coils  and  condensers 352,  353 

engine 349 

gas  engine 350 

ice  cream 382 

ice  delivery 380 

ice  storage  plant 310 

Pipes 355,  356 

pumps, 351 

rinks 382 

turbines 349 

warehouse '.  383 

Deepwell  pump 298 

Dehydrator 33,  34 

De  la  Vergne 116,  118,  120 

machine 30 

freezing  tank 273 

Dense  air  machine 57 

Density  of  salt 258 

Deodorizer 284 

Depreciation 206,  379 

Design  of  pistons 435 

piston  rod 435 

Determination  from  Le  Blanc  machine  test 451 

amount  of  ammonia  and  air 420 

amount  of  water  for  condenser  and  power 432 

of  best  quantity  of  water 440 

of  best  thickness  of  cork 407 

brine  pipe  and  pump 423 

bunker  surface 421 

coefficient  of  wall 408 

coil  surface 427 

condenser  surface 436 

cooling 399 

cost  of  pumping 429 

data  for  air  drying 444 

fan  and  power 422 

heat  loss  through  walls 413 

ice  storage 428 

length  of  pipe 419 

multiple  effect  installation 438 

number  of  cans 426 

Pipe  sizes 43S 

plate  plant 426 

radiation 418 

refrigeration 396,  398,  428 


460  INDEX 

PAGE 

Determination  refrigerating  effect  test 449 

size  of  air  compressor 431 

size  ammonia  main 425 

size  of  cooling  tower 442 

of  size  of  evaporator 430 

size  of  filter 431 

size  of  freezing  tank 425 

specific  heat 398 

storage  space  required 410 

value  of  ice  storage ". . , .  428 

of  valve  area .  .  . : 435 

velocity  of  brine 420 

water-cooling  system 448 

Dexter  system  of  refrigeration 1 1 

Diagram  of  cycle 66 

Dickinson 16,  258,  308 

Diffuser 167 

Dimensions  of  boilers .  .  . 365 

compressors 358,  360,  361 

Dimensions  of  engines 362 

generators 368 

motors 369 

producers 367 

turbo-generators 363 

Direct-expansion  system 5,  27,  245 

Displacement 7° 

Distilled  water 79 

Distilling  apparatus 280 

,  cost  of 357 

Distribution  of  air 246 

Door,  heat  leakage -, 416 

construction 208 

Drinking  water,  cooling 331 

computations 335 

for  hotels 338 

Dry  bulb  thermometers 5° 

compression 68 

Drying  air 3T9 

Duct,  size  of 248 

Dump,  ice 290 

Dust  preventing 222 

Dynamic  pressure 25° 

E 

Efficiency  apparatus 347 

Eggs 22° 

,  candling 22° 


INDEX  461 

PAGE 

Eggs,  cracking 221 

,  temperatures  of  storage . . ; 222 

,  weight 220 

Elbows. . 143 

Electric  generators,  cost  of 350 

motors 115 

welding 140 

Elevator 238 

Engines,  cost  of 349 

,  data 349 

,  dimensions  of 362 

,  steam 115 

Equivalent  speed 252 

volume 252 

Ethyl  alcohol 105 

Evaporating  surface,  effect  of  varying 306 

Evaporation,  heat  of ,.      a 

Evaporator,  refrigeration  by 26 

,  design  of 283,302,307,430 

Excavation  costs 244 

Exchanger 34,  137 

Expander 66 

Expansion  coils 31 

,  storage  of  ammonia  in 123 

for  freezing 306 

joint , 262 

valve 31,  289 

F 

Fan  blowers,  cost  of  and  dimensions 352,  353 

data 251 

,  size  and  power :  422 

Fermenting  tank 241 

tub 315 

Filter 276,  286 

size  required 431 

Fish 225 

Flange  union 141 

Flooded  system 288 

Floor  construction 207 

insulation 204 

costs 345 

Fore  cooler 284 

Freezing  by  evaporation 37 

,  coils  for .... , 306 

,  tanks 303 

,  time  of 304 


462  INDEX 

PAGE 

Freezing  tank 273,  288,  303 

,  size -. 425 

Frick  Co 27 

machine 28,  122,  123,  124,  275 

Friction  effect 44 

loss 249 

Fruit 227 

Fuels 348 

Furs 229 

Fusion,  heat  of 2,  215,  308 

G 

Gauge  board 29 

Gas  Engine 115 

,  cost  of 350 

,  data 350 

Gayley 319 

Generator 32,  134 

dimensions 368 

George. 258 

Gobert  system 329 

Goods,  heat  from 416 

Gorrie 21 

Grapes 228 

Grease  separator .  . 285 

H 

Hall,  J.  &  E 26 

Hampson 340 

Hangers 146 

Hart  cooling  tower 171 

Haslam  &  Co 26 

Haynes 38 

Head  cushion . -. . .   109 

Headers 273 

Heads 117 

,  false 119 

,  spherical 121 

Heat  content 59 

-entropy  diagram . . . .  * 61 

for  breweries 317 

hem  door  leakage 4*6 

goods 416 

men 4J6 

loss  from  pipe 334 

in  cold  storage 243 

per  year .,,,,, 408 


INDEX  463 

PAGE 

Heat  of  air  leakage 213 

complete  absorption 81 

partial  absorption 81 

complete  dilution 81 

fusion 2,  215,  308 

lights 214 

machines 214 

persons 213 

solution 3 

of  salt 14 

vaporization 2 

transfer 182 

through  walls 190 

transmission 184 

Helmets 1 79 

Hoofnagle 38 

Hoists 290 

Horse-power  to  drive 47 

Hotel  air  cooling 322 

boxes , 238 

Hydraulic  radius 249 

Hydrometer,  correction  for 295 

Hygrometer 50 

I 

Ice,  amount  of  refrigeration 310 

and  salt  mixture ; 223 

,  artificial , 5 

,  manufactured 5 

,  can 289 

cold  storage 241 

cream  data 382 

cream  freezer 326 

consumption,  curve  of 308 

,  cooling  by 3 

,  cost  of  storage 309 

,  delivery  data - 380 

,  distribution 310 

,  dump 290 

,  heat  of  fusion 308 

,  latent  heat  of  fusion 41 

making 265 

,  absorption  system 297 

,  passenger  car 382 

plant,  Frick 275 

,  York 270 

saw 279 


464  INDEX 

PAGE 

Ice  storage  amount  and  economy 428 

plant  data 310 

room 276 

tank  insulation 208 

Inclined  coordinates 62 

Incomplete  expansion 48 

effect 48 

Indicator  cards 41 

,  from  vapor  machines 64 

,  use  of 113 

valve 29 

Indirect  system 246 

Injecting  liquid,  effect  of 119 

Insulation 190,  201 

,  amount  of 244 

,  cost  of 345,  346 

,  experimental  determination  of  value 212 

values  of  K 211 

Insurance 206,  379 

Interchanger 33,  37 

Interest 379 

Interstate  Commerce  Rules 181 

J 

Jacket 1 26 

,  effect  of 112 

Jackson  system  of  refrigeration 9 

Johns-Manville  Co 131 

K 

Kirk 21 

Kroechel  machine 128 

L 

Labor  for  plants 373 

Lagging 112 

Land  cost 343 

Lantern 112 

Latent  heat 2 

of  fusion  of  ice 41 

Laws,  cold  storage 217 

Le  Blanc 39 

machine  test 451 

Lightfoot  machine 19 

Lights,  heat  of , • 214 

,  heat  from 416 

Lillie  evaporator , 300 


INDEX  465 

PAGE 

Linde 340 

Liquid  air 340 

Liquid-air  machines 341 

Liquid  line 58 

Liquid  receiver 341 

Lith 201 

Load  factor 375 

Lorenz 329 

Loss  of  heat  per  year 408 

Low  temperature  by  ice  and  salt . 16 

Lubrication 121 

Lucke 80 

Lumber,  costs 344 


M 

Machine,  absorption 31 

,  Carbondale 36 

,  York 35 

Allen  dense  air 19,   57 

compressed  air 4 

,  heat  of 214 

,  Lightfoot 19,  57 

,  test  of 400-405 

Machinery,  costs 347 

Marine  compressor 1 29 

Market 232 

Masonry  costs 344 

McCray  refrigerator $ 

Methyl  alcohol 105 

chloride 31,  105 

Meat 223 

Melons 229 

Men,  heat  from 416 

,  required 373 

Milk 225 

Mill  work,  cost  of 345 

Miscellaneous  apparatus 357 

Motors,  dimensions  of 369 

,  electric,  cost  of 350 

for  driving  compressors 115 

Moisture  effect 50 

Mollier 80 

diagram 63 

Multiple  effect 107 

,  installation 438 

,  Voorhees ,  < ........     71 


466  INDEX 

N 

PAGE 

Nozzle  design 178 

steam 167 

O 

Oil  pump ng 

separator. 31 

spray 117 

Onions 229 

Open  air  system 20 

Operating  costs 376,  377,  378,  379 

Operation  of  cylinders 1 23 

Oranges 228 

Osborne 16,  308 

Ott  Jewell 297 

Oxy-acetylene  welding  . 140 

Oysters 227 

P 

Packing  house 239 

,  leather 1 29 

Painting,  cost  of 345 

Partial  pressure  from  aqua  ammonia 80 

Partial  absorption,  heat  of 81 

Partition,  cost  of 345 

Passenger  car  ice 382 

Patten 38 

Peaches 228 

Pears 227 

Penny 169 

Performance  of  plants 370,  371,  372 

Perkins '. 4 

Perman 80 

Persons,  heat  from 213 

Pipe  and  fittings,  cost  of 354 

Pipe  coefficients 255 

covering 200,  346 

data 355,  356 

for  storage,  cost  of 357 

heat  loss , . 334 

joints 142 

length,  determination  of 419 

lines,  bell  and  spigot 262 

line,  brine 262 

line,  size 257 

,  size  at  compressor 435 

,  size  of 3°8 


INDEX  467 

PAGE 

Pipe,  suction  and  discharge 119 

Piping 138 

arrangement 236 

for  brine  tanks 259 

for  bunkers 256 

for  rooms 256 

Piston 27,  109,  129 

,  arctic 126 

design 435 

rod 121 

rod  attachment 121 

rod  design 435 

speed 434 

Planck 75 

Plant  cost 376,  377,  378,  379 

Plate  plant,  size  of 426 

Plate  system 269,  276,  297 

Plumbing,  cost  of 345 

Plums 228 

Poetsch  system  for  shaft  sinking 328 

Point  of  boiling 2 

fusion 2 

melting 2 

Pond,  cooling,  design 178 

Poultry 224 

Power  for  deep  well 300 

plants 370,  371,  372 

raw  water  ice 296 

to  drive 106 

Precooling  cars 264 

charges 382 

Pressure,  effect  of  varying 307 

volume  diagram 64 

Principle  of  refrigerating  machines 5 

Problems,  absorption  machine 83 

,  air  machine 55 

,  vapor  machines 72 

,  miscellaneous 407-451 

Producers,  cost  of 348 

dimensions 367 

Properties  of  ammonia 387~389 

of  carbon  dioxide 390-392 

of  sulphur  dioxide 393~395 

Pump,  air  lift 298 

,  cost  of 351 

data 3Si 

,  deep  well 298 


468  INDEX 

PAGE 

Pump,  oil 119 

Pumping,  cost  of 429 

Purge  valve 29 

R 

Radiation 182 

,  required 418 

Raw  water 79,  269 

system 290 

Reboiler. 274,  282,  284,  285 

,  vacuum : 283 

Receiver 161 

Receiver,  cost  of 353 

Rectifier 33,  34;  136 

Reduced  pressure 3 

Refrigerants 105 

Refrigerating  capacity 41 

effect 46 

effect,  vapor  machines 70 

effect  from  test 449 

machine  compression 26 

machines,,  general  principle 5 

machines,  diagram  of  cycle 66 

mediums 31 

plants,  cost  of 347 

Refrigeration 46 

applications  of 312 

automatic 263 

by  chemical  process .  .    40 

ice 8 

evaporation 26 

,  central  station 260 

,  determination  of 396,  398 

for  brewery 317 

creamery 339 

dairy 339 

plant 428 

methods 8 

Refrigerator 8 

cars 13 

household,  data 384 

Relative  humidity 50 

chart 175 

Repairs 379 

Return  bends 31,  144 

Return  tubular  boilers 363 

dimensions  of 363 


INDEX  469 

PAGE 

Rietschel 191 

Rinks 326 

Rink  data 382 

Roadway,  cost  of 345 

Roelker 24 

Roofing,  cost  of 345 

Rooms,  piping  for 256 

Rooms,  temperature  of 244,  413 

Rugs 229 

Rules  for  safety 180 

S 

Safety  devices 1 79 

head. . , 29 

plate 1 29 

Salt,  heat  of  solution 14 

Saturated  ammonia,  properties  of 385-387 

Saturation  line 58 

Scale  separator 31 

Separator 33,  34,  "9,  *59 

,  cost  of 353 

,  oil 31 

scale , 31 

Setting  box 312 

Shaft  sinking ' 328 

Ship  cold  storage 240 

Single  acting  compressor,  advantage  of 113 

Skimmer 283 

Solution,  heat  of 3 

Space,  cost  of 409 

,  storage,  determination  of 410 

Spangler 8c 

Specific  heat,  determination 398 

of  aqua  ammonia  — 83 

brine 15,  258 

chocolate 313 

ice 16 

materials 215 

superheated  steam 44 

vapors 64 

Speed,  equivalent 252 

Spider 109 

Spray  nozzles 172 

Stahl 38 

Static  pressure 250 

Steam  for  plants 371 

washer 300 


470  INDEX 

PAGE 

Storage,  cost  of 215,  375 

tank 31,  287 

unit  for 215 

Strainer II9 

Strawberries 228 

Stuffing  box 27,  112,  117,  121,  126 

Suction  side '. . .     29 

valve 28 

Sulphur  dioxide 31,  105 

machine 131 

properties  of 39i"393 

Supplies,  cost  of 357,  374 

Superheat,  degrees  of 63 

Sweet  water  cooler 241 

Switchboard,  cost  of 350 

T 

Taxes 379 

Tees 143 

Temperature  at  points  on  cycle 19 

-entropy  diagram 57 

mean  difference 185 

of  freezing  for  brine 258 

ice  and  salt  mixtures 14 

rooms 244,  413 

range,  effect  of 78,  79,  106 

Testing  coils 1 24 

Test  of  apparatus 395 

cooling  tower .  406 

machines 400-405 

Tests 395 

Thermit  welding 138 

Thermodynamics  of  refrigeration 41 

Thermometer  comparison 395 

correction 397 

,  use  of 169 

Thomas  spray  nozzle 172 

Thompson- Joule  effect 340 

Throttle  valve 32 

Tilting  table , 279 

Time  of  freezing 304 

storage 215 

Tobacco 229 

Tomatoes 229 

Tripler 340 

Triumph  ice  machine 127 

Tub,  fermenting 315 


INDEX  471 

PAGE 

Turbines,  cost  of 349 

data 349 

Turbo-generators,  dimensions 363 

Twining 4 

Two  cylinders,  use  of 113 

U 

Ulrich 297 

Unions 141 

Unit  for  storage 215 

V 

Values  of  K 187 

Valves 121,  148 

,  cylinder. 117 

,  hurricane 125 

,  indicator 29 

,  manipulation  of 123 

,  mushroom 18 

,  purge 29 

,  sizes 435 

,  slide 18 

,  Triumph  Co 127 

Vaporization,  heat  of 2 

under  reduced  pressure 3 

Vapor  machine 57 

pressure 51 

pension .....; 51 

Vegetables 229 

Velocity  of  air 248 

pressure 250 

Ventilating  air  cooling 322 

Vogt  Co 134 

Volume  equivalent 252 

Volumetric  efficiency 70,  434 

Voorhees 71,  107,  438 

W 

Wall  coefficient,  determination  of 408 

constants 192 

for  cold  storage 243 

heat  loss 413 

Warehouse  construction 231 

data 383 

\Vater,  best  quantity  of 44° 

,  cooling  system  design 448 

,  cost  of 374 


472  INDEX 

PAGE 

Water,  distilled 79 

,  distilled,  amount  required 300 

,  effect  of  large  quantities  in  air 53 

for  condensing 432 

for  cooling 374 

for  ice  making 298 

jacket 29 

jacket,  value  of 29 

per  pound  of  aqua  ammonia 81 

,  raw 79 

storage  tank 273 

tank  insulation 337 

tube  boiler,  dimensions 365 

Weak  liquor  cooler 137 

Welding 138 

Westinghouse 39 

Westinghouse — Le  Blanc  machine 167 

Wet  and  dry  bulb  hygrometer 174 

Wet  bulb  thermometer 50 

Wet  compression 68 

White-wash 222 

Wood  insulation 202 

Work  of  compression 43 

,  air  machine 20 

expansion 43 

with  friction 44 

Y 

York  ice  plant 270 

machine 36,  no,  in 


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